And (to a lesser extent) the equivalent process for other domestic terrorist groups.
People will still understand what you mean if you use "radicalization" to refer to positive things, but they'll wonder if you're making a very dry joke.
* Anyone who drives slower than me is an idiot and anyone who drives faster than me is reckless.
* Anyone who's worse than me at me at Overwatch is a noob, anyone who's better than me has no life.
* Anyone who's views are less extreme than me is a sheep, anyone who's views are more extreme than me is a radical.
It takes a lot of effort to realize that I'm on the "radical" spectrum for a lot of my political views (I'm hella progressive) and that that isn't a bad thing, but neither are other people's, in my view less aggressive, ideas for tackling problems.
It's hard to suss out people's goals. They might not understand their goals themselves, and "goal" may be an abstract and unknowable thing. But I think it's necessary to find some goals to be a bad thing in order to figure out your own politics.
E.g. Gandhi would have been called "radical" without implying any violent tendency.