Government does have a legal obligation to comply with the laws it has passed, SS being among those. Of course it can change laws, but until it does it is obligated to comply.
Contract has a very specific legal meaning. Not sure what this clown thinks he’s accomplished by speaking about SS in terms of contracts. Government does enter some contracts, but it’s not contractually obligated to carry on any of its basic functions. It’s not contractually obligated to maintain an armed forces, and the armed forces have varied greatly in size over the history of the US.
What contract did you sign?