The court has ruled that individuals have a First Amendment right to use Twitter to interact with representatives of the federal government. But you can't use Twitter to interact with those representatives if Twitter has banned you.
No, it hasn't, except insofar as such a right is protected against a specific form of government action.
It has ruled, more accurately, that individuals have the right to not have the government officials exclude them from full participation in particular corners of Twitter used for official government purposes.
Sure, but that end result isn't what the courts have found is prohibited, they have found that government officials excluding people on certain bases is prohibited.