Not really. Such agreements are signed daily. It is rare for them to be violated. The penalty for violating the agreement- which is part of the contract- tends to be very high to provide motivation to not violate the agreement. And if Trump sues, there won't be much of a hearing. Did you sign this (Yes). We have evidence that you violated it. You owe Trump a ridiculously large amount of money to which you agreed to in advance. Hearing over.
One possibility is that anti-Trump groups offered to pay this cost if Stormy would violate the agreement by going public.