It is legal to sell that in most countries, if not all of them. The point is they have to be sold by prescription, which I doubt is required in these threads.
Why don't you post links? Those threads break the rules and you will make it easier for the mods to find them to trash them.
I had a look in the goods section but I didn't see those threads.
This has nothing to do with freedom of speech.
Because they are busy, and the threads are not so easy to find, I guess?