In my view, the arguments that the contract is void for violating public policy are much stronger than the lack of signature argument. Those arguments are worked into the amended complaint. There are a whole lot of arguments as to why the contract violates public policy, only one has to work.
There is another problem with claiming Trump is not a party. The contract says he has to be or the contract is not valid. The agreement says “Trump warrants” various things. That means Trump has to do that. He can’t warrant that which he does not even know about.
Further, the agreement states that what Trump warrants are “material inducement” to Stormy Daniels and that without them she would not have entered the contract. So if Trump didn’t warrant that, which his attorney says Trump could not have done, then the contract is void for fraud in the inducement.