He contractually waived the right to call them out on their figure. What Twitter is doing is performative; they're living up to the letter of their covenants in the deal. They don't have to prove anything to Musk. He's on the hook.
They didn't want to be the target of a pump and dump. And they didn't want a bunch of distracting rumors from a takeover bid with no financing. As soon as Elon put financing together they said "yes" pretty quickly.
Shareholders can only sue Twitter if those facts are materially false. This is an incredibly high bar that is almost never met.
;)