It seems like the thesis here is that whether or not "non-trivial" Javascript (which is just about all Javascript in the wild) should be trusted depends on the presence of an explicit GPL license. If so, that doesn't seem like a reliable heuristic for a script blocker to me.
I'm pretty sure it would be similar to ad-blockers. The initial implementations are trivial and easily circumvented, but as they evolve they become more useful overall.
Plus note that I was just suggesting that it would be more effective than a social movement with 'ethical repositories'. Just imagine if the ad-blocker devs tried the same strategy...
