Your explanation makes sense to me. This poster didn't say that meetings with past Buddhas were possibly an important factor in his awakening. He said awakening was impossible without studying under a Buddha.
Here's the gentleman's quote: "... the good priest states that early Buddhism (the Buddhism of the Pali texts) taught that there was no "intermediary" needed between the unenlightened human being, and Nibbana/Nirvana. That's a common misunderstanding in the West. In fact, the Pali texts show that whoever realizes Nibbana/Nirvana, realizes it by studying under a living Buddha. No one becomes a Buddha, without studying under a Buddha."
Am I correct in thinking that he is mistaken here?