He's had trouble securing funding and basically has buyers remorse.If he can actually prove the number of fake accounts is significantly wrong, that'd be a slam dunk in court. That'd break the merger agreement in multiple ways.
He has a contract with twitter under what conditions he can back out. I've read into it a lot and tbh Elon is probably screwed here. Twitter will sue to enforce the contract and Elon will have to prove his exit conditions were met. He's trying to proclaim the numbers around "fake accounts" is his reason. If that is his legal strategy he is beyond fukt as it won't hold up in court.
However it seems his primary legal strategy is that Twitter failed to provide him with requested data in a reasonable manner. Musk's lawyers have been perusing this avenue since at least June 6.
