Enabling and endorsement are two different things, no need to conflate the two. If I'm a dentist and tell my patient that they could use any toothpaste they want but that I don't recommend the specific brand that they use, how is that an endorsement in any way? I'm allowing them the choice without endorsing in this case.
In your analogy, the dentist is selling the bad toothpaste and saying "Go pick any from the shelf over there but not that one". Why is he selling it then? The dentist can't say "well it's a free market" as if that somehow absolves him. He sells the bad toothpaste, that's a tacit endorsement.
You can be a proponent of free speech and not allow people to stand on your porch yelling heinous things, but that's not what Reddit was doing. They knowingly profited from that speech.
