overall, saying "not dependent on words or speech" is border line nonsensical
It is nonsensical, but only if you use conceptual thinking to try to understand it. Bodhidharma was known to give people copies of the Lankavatara Sutra. It details the shortcomings of words and speech. It says things like this:
Then Mahamati said: Again, Blessed One, are words themselves the highest reality? or is what is expressed in words the highest reality?
The Blessed One replied: Mahamati, words are not the highest reality, nor is what is expressed in words the highest reality. Why? Because the highest reality is an exalted state of bliss, and as it cannot be entered into by mere statements regarding it, words are not the highest reality. Mahamati, the highest reality is to be attained by the inner realisation of noble wisdom; it is not a state of word-discrimination; therefore, discrimination does not express the highest reality. And then, Mahamati, words are subject to birth and destruction; they are unsteady, mutually conditioning, and are produced by the law of causation. And again, Mahamati, what is mutually conditioning and produced by the law of causation cannot express the highest reality, because the indications [pointing to the distinction between] self and not-self are non-existent. Mahamati, words are these indications and do not express [the highest reality].
A direct expression of the highest reality does appear completely nonsensical. But appearances can and are deceiving. Case 14 of the Mumonkan (Book of Koans) is a very good example
Mumonkan - Nansen Kills a Cat
Once the monks of the Eastern Hall and the Western Hall were disputing about a cat. Master Nansen, holding up the cat, said, "Monks, if you can say a word of Zen, I will spare the cat. If you cannot, I will kill it!" No monk could answer. Nansen finally killed the cat. In the evening, when Joshu came back, Nansen told him of the incident. Joshu took off his sandal, put it on his head, and walked off. Nansen said, "If you had been there, I could have saved the cat!'*
So here, Joshu delivered the "one word of Zen", that could have saved the cat, without even opening his mouth. When I first encountered zen, I did think this was completely nonsensical, Some guy putting a shoe on his head? WTF, this is ridiculous! But it really isn't, it has a much deeper meaning.
and it is never the case that someone can convey zen completely without speech or words.
I don't think that it the case. It can be conveyed, but the issue is whether or not the other person understands the conveyance. Joshu conveyed it in the below koan.
Case 38 of the Mumonkan An Oak Tree in the Garden
A monk asked Joshu why Bodhidharma came to China.
Joshu said: "An oak tree in the garden."
Mumon's comment: If one sees Joshu's answer clearly, there is no Shakyamuni Buddha before him and no future Buddha after him.
Words cannot describe everything.
The heart's message cannot be delivered in words.
If one receives words literally, he will be lost,
If he tries to explain with words, he will not attain enlightenment in this life.
lol! you're totally right! there is zero point in trying too argue logic into any zen statements! it's a tradition that relies heavily on non logical statements and statements that are incorrectly worded (as far as logic and proper social interaction are concerned). and the idea is always that you should look at it from a different perspective that is totally different than the way you normally do. saying anything in zen makes no sense can so easily be argued it's amazing. i don't know what i was thinking. seriously, totally sarcasm free.
it is a little frustrating, but it is entirely true! every statement can mean what it should mean, or something TOTALLY different! "not relying on words or speech" taken literally does imply pantomime or telepathic instruction, so i certainly am correct in that sense. but taken in a "zen" way can mean whatever the heck you want it too mean, so i am totally wrong in that sense.
one point i want too make though is you said:
I don't think that it the case. It can be conveyed, but the issue is whether or not the other person understands the conveyance."
if the other person doesn't understand, then they are not being taught anything. for something too be "conveyed" successfully, there must be positive results in a recipient form. your idea of it being conveyed but the other person doesn't understand is a conveyor belt that drops things off into an abyss instead of loading them onto a truck. it failed too convey it's product too the desired location. if this is the only type of conveying a teacher did, they would have zero results. conveying things that the student does not understand is not teaching. even if the method theoretically could teach the right person. it would be like a theoretical physicist writing extremely advanced equations and theories on a blackboard for a group of people that do not know anything about physics, math, and that cannot even read. the teaching is correct, the method sound, but the students do not have the ability too comprehend, so the teaching is a total waste. whereas if the teacher explained it in a language they understood, there would be progress, and eventually they could work up too getting it. but again, the point is you can't have JUST this kind of super advanced teaching method, there HAS too be words and speech.
yes, a koan makes no sense at first but one can work up too understanding, but this working up too understanding is totally reliant upon having learned how to practice the koan, why too practice it, what zen is, etc., etc. and every single step of the way, including the speaking of the "oak tree in the garden" koan, involves words and speech.
also, if someone teaches zen only through pantomime, hitting and shouting, no one will ever learn zen from them. i suppose one could argue that with twenty or thirty years of dedicated viewing of this teacher a student could learn, but that's a stretch. even so, the bottom line is: not a single teacher has EVER taught entirely without using words and speech. it's unheard of.
really this is pointless semantics though. you really nailed it on the head with:
It is nonsensical, but only if you use conceptual thinking to try to understand it.
seriously, this is a classic, unbeatable zen style argument-destroying statement. if you had stopped there i wouldn't have rambled on about conveyor belts and all the other nonsense lol! thanks for taking the time though