Would you say the same exact thing about the phone companies?

Phone companies are platforms in the same exact way. Do you believe their 1st amendment rights are being taking away, because they can't "deplatform" phone calls from people they don't like, or from their competitors?

If the choice of deplatforming someone is a 1st amendment speech act (which I am ok with), then the choice to not do so needs to be a prosecutable offense (at which point you are just arguing that everyone should be a "publisher"). (Then, if websites can't manage to exist in this legally-consistent regime, maybe we finally get research into distributed systems in order to have true "platforms".)

Did you miss a "not" there or are you saying deplatforming should be a requirement?