You are conflating The First Amendment (a law) with Freedom of Speech (a principle).

FoS is something we should support in any context because the only speech worth hearing is the stuff you don't like hearing.

This seems rather ironic, since TD was banning people that went against the majority opinion.

If TD is repeatedly violating freedom of speech principles what exactly is your recourse to ensure they comply and adhere to freedom of speech? If we accept that TD has the right to ban users it doesn't like, then we accept that Reddit has the right to ban subreddits it doesn't like.

> the only speech worth hearing is the stuff you don't like hearing

What's an example that supports this? I can only think of examples that indicate the opposite.

To repeat a trite argument, that is the case for the free speech that is guaranteed under the US constitution. Free speech advocates usually claim that either reddit does indeed violate that constitutional right (similarly to how it applies to federally funded private companies) or that the human right of free speech is violated.

This second version is assumed to exist a priori from any state/law similarly to how international human right conventions Recognize human rights rather than Create them.

Which is a nice loophole when we know the battle for votes is primarily fought on social media

Doesn't the concept of freedom of speech necessitate the freedom from speech, ie. the right to remain silent? To force a company to say something they don't want to is in my opinion worse than allowing them to say nothing. I don't expect Breitbart to voice my opinions, for instance, and I don't expect Twitter to voice theirs if they don't want to.