Free speech is totally a restriction on the government and we have morphed it to being every private entity can not restrict anything.
"Free Speech" is not a restriction on the government, it is a right everyone is born with. The First Amendment is a restriction on the Federal Government to prevent it from interfering with that right.
Pointing out that a private entity interferes with Free Speech is a reasonable thing to do even though the First Amendment does not apply to them, because the right to it exists outside the First. In Twitter's case the government did not take legal action for restricting Free Speech. People who thought they could better meet Twitter customers' needs bought them and are starting to run it according to their principles. To the extent there is a free market that is the free market at work.
