I don't have a good answer for where the line is, but at least in the cases of bin Laden and Kashmir, normal channels for arrest and extradition wouldn't have worked. I'm less sure about Eichmann, but according to Wikipedia, Argentina had a history of refusing to extradite Nazis.
In this case, China shouldn't have had any trouble getting Hong Kong authorities to arrest and extradite this person, so it doesn't seem like the same thing.
In this case, China shouldn't have had any trouble getting Hong Kong authorities to arrest and extradite this person, so it doesn't seem like the same thing.