In the Twitter thread you linked to in your article, Ali Aydar made the comparison to Wikipedia, not Tony.

I looked up the YouTube video you mentioned and searched the transcript (not wanting to watch an hour-long video right now). At 49:34 (https://youtu.be/Zd445DkS2JQ?t=2974), Tony says that if we were to organize the best of Medium's 75 million blog posts, "we would have a knowledge base on par with Wikipedia, covering different topics".

Tony can clarify for himself, but I don't think he's actually trying to make Medium "the next Wikipedia". Speaking as a long-time Wikipedia editor myself, in addition to a Medium writer, they're completely different kinds of platforms.