but it is part of the deal, given that twitter says "bot % is <=5", now he may believe that not to be the case. I think its concievable he may have acted before he fully considered whether that number indeed is true

Would he need to show it isn’t true?

And prove that’s enough of a reason to end the deal?

one would think so, so it will be interesting to see how he argues that, but the contract does include more things, including twitter having to provide anything required to obtain funding, which one would probably strongly be able to argue covers data to independently verify this