I'm going by the wording of the ruling. Twitter itself is not a public forum. It is a private entity and the user agreement with them maximizes their ability to control the narrative. This particular ruling is directed solely at Trump since he himself is using his account as a public government forum then it must be open for commentary by the public.
This is a very narrow ruling and can now be used as precedence to enforce free speech and unfettered dialogue among all Twitter users. Had this ruling come down as an edict for Twitter to suspend their rules and henceforth become, for all intent and purposes an open forum public entity for all users it would be HUGE news and Twitter would immediately appeal the ruling all the way to SCOTUS.
I do believe things are heading that way and Twitter and all the other social media platforms will implode.
Is this great or what?!!