You can clearly define and enshrine intolerance based on immutable physical characteristics into speech laws, as many countries have done (Canada, Germany, etc).
Sorry, this is not a "clear slippery slope fallacy".
A slippery slope fallacy is a claim about a series of events, with each even being more unlikely than the one before it. GP makes no claim of a series of events at all.
GP is merely pointing out that often, societal norms have been immoral, despite the "wisdom of the time" saying that challenging the norm is immoral. And society doesn't realize they were wrong until the normal has been challenged. By not allowing a society to challenge the norms, the norms may never change.
It is your example that is fallacious. You bring up Canada and Germany, even though we have no idea how good or bad of an impact those laws will have. And more importantly, how dangerous it is to even give a government power to restrict this sort of speech. We don't know the conclusion.
Sorry, you missed something. The parent post literally called out the next step on the "slippery slope": "but what about when they cut funding for your Mastodon server or phpBB board because of a few posts you've put up they don't like?"
> You bring up Canada and Germany, even though we have no idea how good or bad of an impact those laws will have
This makes no sense. We literally do know how good or bad of an impact these laws will have _because there are literally examples of countries with those laws_.
The example in this article is a little different because Epik was cut off because their cryptocurrency operation didn't make any attempt to be right with the SEC.
As far as Canada goes, Mike Ward was fined $80,000 for making a joke. Mark Meechan was fined £800 in the UK for a comedy routine where he taught his dog to make a Hitler salute. I have personally know many Germans who have told me there are things they cannot criticize or say because they are German (referring to the Israeli/Palestine conflict).
You can clearly define and enshrine intolerance based on immutable physical characteristics into speech laws, as many countries have done (Canada, Germany, etc).