You just saw it but there's no any other explanation why he'll invest on ADA and not even a single proof that he said he'll be on it. You know in the bull market, when a known personality invests into a coin, then also put it on hype to make it look like he's investing into another coin.
Whoever made that rumor, he has successfully made people believed that it's a real thing. ADA is also one of the top coins these days but no need to make some misleading tweets or rumors.