You've made the case that SS is not a Ponzi by definition and that these safety nets exist for a reason.
You have not made a case for why the people should be paying this tax under threat.
You also haven't made a case for why SS is sustainable, which is why Musk called it a Ponzi.
If the entire argument is based on semantics and the definition of what 'Ponzi' means it's not a very strong one.