Historically, some of the most discriminated people have been people of a different religion. In principle you can "stop believing in your religion" as easily as you can stop believing that immigrants are destroying your country.

In practice, nobody cares to protect bigots and a lot of people want to protect gays, immigrants, women, etc. It is troubling that we only protect certain classes of people since maybe the next group that comes along after the current group of bigots will actually deserve protection but the arguments we built to allow the lack of protection for bigots will be used to deny protection to that group.

That doesn’t change the fact that the CRA restricted freedom of association. Still, the better argument for legislating platform neutrality is that those platforms enjoy special legal status based on the notion that they can’t be held responsible for user-generated content. If you can spare resources to purge content that offends your political sensibilities, then you are making a choice not to remove content that is, e.g., defamatory, infringes on copyright, etc.