As was said, this is just a slippery slope argument. Which is especially odd considering the platforms already have all the power they need. There is no more power to give.
Ability to censor top level politicians, deciding what constitutes acceptable and what needs to be censored is not the kind of power they used to have.
This isn't true. Private entities have never been required to distribute messages from US officials or politicians. I believe the only exceptions are certain emergency broadcasts.