For clarification: The 1st amendment ensures that the government may not stop you from saying what you want. This is a separate issue from private companies removing/banning you. Each company has their own right and freedom to be as dickish as they want with regard to deleting your account etc - but that is not related to the 1st.
Ether you are aware that people are appealing to free expression as a principle, or you are unaware that free expression is more American than apple pie. That’s why I say this retort is disingenuous.
So the legal scope of the literal first amendment doesn’t help the discussion on what people and companies should be doing.
The discussion is about American values and if people, companies and the government should be living up to them. And that’s what people are trying to debate when they say “first amendment”.