I assert that your refusal to do business with Reddit sends a clear message that it should not be allowed to operate. Your actions are speaking louder than your thoughts here.
Is free speech not worthy enough to be blindly defended?
In your world, I am not free. A store near my house sells Confederate flags. Can I stop shopping there? No, because that sends a clear message.
A racist is on a street corner calling for ethnic cleansing, and waving pictures of black people being lynched (found via Reddit, by the way). Can I turn tail and walk away, denying them my attention? Once again, that sends a clear message.
A racist pops up out of nowhere on Twitter and tries to apply some foolish argument. Can I block them, and thus never read what they have to say? Again, ignoring them sends a clear message.
If I can't choose where I spend my money, who I associate with, and who I listen to, what kind of freedom is this?
I appreciate it's muddy water here, but it doesn't seem like a simple case of free speech.
These are internally-moderated groups (i.e. not really free speech to start with for regular folks) that form echo chambers in which hate groups can fester and evolve their groupthink.
Try and imagine something like that happening offline, where a group's ideas separated them from wider society, and their speech was governed so absolutely by a small number of leaders. The closest comparison I can think of is a cult.
Cults are broadly legal, but their tight structure, disconnection from wider society, and the fact that they disproportionately attract vulnerable minds mean that they at least need some policy consideration.
I don't claim to have an answer, I just think the problem is more complicated than 'free speech, defend it blindly'
Is free speech not worthy enough to be blindly defended?
I think it is.