Are they going to take the same stance to videos about gaming, because gaming addiction is a real problem and a progressive diet of “Lets Plays” normalizes unhealthy amounts of video games, by showing people whose entire life is video games?
I can't believe I have to say this, but it's different because political beliefs, whether they inspire one to shoot a bunch of people or just to vote for the "burn it all down" party can have a damaging influence over society as a whole. I.e. it's not just about the personal responsibility to oneself as much as the risk of being inspired to terrorism.
The banning of dissent under the pretense of radicalism has harmed more people than terrorism — Stalin’s purges, Mao’s purges, heck, even Hitler was just clearing out the seditious members of society who were undermining a strong Germany.
Your arguments, however you mean them, are also those used by tyrannical oppressors to justify the powers they use to commit great evil.
In an (unintentional?) irony, all of those people you cited rose to power and did great damage to their societies by exploiting radicalism in politics.
Gaming addiction is a systemic problem that’s impacting the social stability of several Asian nations, and possibly Western ones — your argument isn’t principled, merely special pleading.
Why is that different than politics?