In three years, the slippery slope has gone from deplatforming a tiny handful of online Nazis to deplatforming the President and an app with 10 million users.
Well, in three years the president has gone from claiming that there were more people at his inauguration than there actually were, to undermining democracy by persisting for months in his claims of election fraud despite failing to produce any evidence for it in the courts (while ignoring a pandemic that is currently killing 3000 people a day in his country). How about that for a slippery slope?
I'm not sure the concerns of censorship change due to who or how many are espousing the toxic calls to violence. Nazi Germany had a Chancellor/Dictator, with 8.5 million in the Nazi party in 1945. The reason it's okay to deplatform Nazis today is not because their numbers have dwindled.