You can ask the question of whether you think in general that marginalized voices should be allowed to exist. Obviously, you don't like these particular people (and neither do I) so you don't see any problem with eradicating their voice. If Amazon were just one provider and there were other options it might even then still be OK. But it's not just a choice of Amazon. Any provider hosting them will be subject to the cancel mob.

Picture instead private businesses who all refuse to do business with Jews. Anyone who does business with them are subject to reprisal and boycott by their vendors, friends, and neighbors. The Jews themselves of course are fired from their jobs if anyone finds out they're a Jew. In practice the Jews cannot do business and must live a marginalized existence or hide who they are. So it's not enough to say "well it's a private business they can do what they want" when you would not consider this valid in other contexts.

And of course all this is ignoring the question of whether any of this is likely to be successful in the end or if it will further justify reprisals and enrage anyone subject to this mob justice. Certainly all the tech companies banding together to silence politics they don't like plays exactly into the narrative the far right is pushing.