I think it's totally fair to ask the question, given that he seems to be involved in starting a competing organization.

> He's the world's best chess player of all time

This one is hard to tell because not all of them have been alive at the same time. Morphy was really, really good, but in the 1850s.

Currently there's Ivanchuk, who is good enough to beat anyone but has no stamina so can't win tournaments reliably enough to be world champion.

There’s no way Morphy at his peak would beat Magnus at his peak (and the same goes for any of the old champions)— The way chess is played today is very different. Morphy would have needed to start from scratch and re-learn the game today from a young age to have any chance… But then he wouldn’t be the same Morphy.

Or maybe Magnus wouldn't be able to cope with how Morphy plays the game and would lose. Both of them were/are used to how the game was played in their time.

magnus likely has every game morphy ever played, along with all of his contemporaries memorized, along with at every position in each game, what a strong engine would prefer as a move. morphy would probably be an IM by todays standards, without modernizing