"A lot of very smart people have worked on this problem over the last 80 years or so, and none of them found an elementary proof that could fit on a single page. If they couldn't do it, there is no reason to believe that you have." that is stating it, in short it is saying if people of the past couldn't then no reason to believe me or someone in future can't. Although I will say I can't remember the exact word so will assume this is what he originally said.
What I meant by abusive or now as you say blunt was him saying He won't read the "proof" and then said same as above user: