When Facebook acquired whatsapp, I remember reading that it wasn't the tech per se that facebook really wanted. It was the daily active users. Whatsapp had (still has? dunno) a pretty big userbase. That was the where a lot of the value lay for facebook, or so I understand.
So, if daily active users are important to the value of the property, do we believe twitter's SEC filing estimates of <5% bots? Musk doesn't, or hasn't been convinced by what he has seen.
That really does seem like a legit reason to abort the deal. Twitter is representing <5% bots. Musk thinks that's a wildly optimistic estimate & is prepared to call bullshit. Seems fair to me.
A more cynical view might be that Musk is simply looking to lower the price. Exposure of Twitter's bot problems in a court might not be very good for the share price. Just having Musk pull out (9 kids, he never pulls out) probably dips the share price. So, isn't it all good leverage to bring the price down?