He's alleging several material breaches of the agreement, and that usually is grounds for walking from the deal without having to pay a break fee (I haven't read the merger agreement but I've spent 20+ years negotiating these types of deals and I assume the deal provisions are pretty much what any public company deal has).
Usually, if you walk from a deal because you couldn't get regulatory approval, for example, a break fee is due, but when you allege that there was fraud or a significant breach of the material terms of the contract that leave the target with a value far less than originally expected, no break fee is due or payable.
Musk's counsel (Skadden) is very good and I've had to fight them before on mergers...Twitter is in for a heck of a battle.
