For it to be relevant, the "material adverse effect" needs to have been caused by an action by the company subsequent to the deal being signed. Like, for example, the corporate treasurer suddenly going to Vegas and losing the treasury on blackjack.
Twitter may well have been grossly lying all these years, but the time to figure that out is before you sign the deal. That's kinda the point of doing due diligence.
The merger agreement requires Twitter to provide adequate access to data requested, if they haven't done this then the merger agreement has been violated even without a MAC violation.
Specifically, the merger agreement requires "all information concerning the business ... of the Company ... for any reasonable business purpose related to the consummation of the transactions".
Seems like an arbitrary API rate limit could easily violate this clause. How are you providing "all information [...] requested" if you drip feed it?
The fact they'd even play cloak-and-dagger with this information suggests there's fraud again. Companies with nothing to hide don't mislead acquirers.
You're using lots of words that imply malicious intent and bad faith, without providing anything to back that up.
Not to mention that your theory of Twitter behaving fraudulently in the context of this transaction makes no sense. They've got a commitment to purchase them at vastly more than their market value, so they're highly motivated to see the deal close. What's the incentive for acting in bad faith?
Twitter may well have been grossly lying all these years, but the time to figure that out is before you sign the deal. That's kinda the point of doing due diligence.