I am not sure if Tmingyur means something along the lines of "If you see the Buddha in the road, kill him."
It doesn't quite seem that way. But if he was
riffing on that idea, then it is about not getting attached to an external representation of "Buddha", outside of one's own mind, right? But then Tmingyur also has problems with the notion of "Buddha Nature", so that can't be what he's getting at.
The thing about having a realized being (Bodhisattva, Buddha, etc.) show us the kindness of
overseeing our purification, is that whenever we begin to cling to one thing or another, even at a certain point
the outer form of the teacher themselves, a true teacher will always immediately assist you in cutting that tendency. But as for this latter type of clinging, this is only an obstruction once one has actually achieved a very advanced level of realization, -when one's mind is truly no different from the Guru, or Buddha himself. At that point looking myopically to the external teacher is just another habitual tendency. But for most of us, we are at the stage where we need to cultivate precisely great devotion, respect, gratitude and pure-vision towards our teachers, especially if they are our Vajra Gurus. . . and to put great trust in them, rather then our own deeply ingrained habitual emotional and intellectual traps. This is the only way to begin the practice of Guru yoga, which is the essence of the path, where our minds can actually merge with the wisdom minds of our teachers. This is, of course, a Vajrayana belief. But Vajrayana is the natural extension of Mahayana, it is still Mahayana in essence. So I don't believe the Mahayana systems differ in many respects on this point. Looking at Zen Roshi's and their relationship to disciples, for example, there seems to be a lot in common. What Mahayana tradition is there where teachers are viewed as disposable?