Yes, it can be abused, innocents can end up being charged with a crime they are not responsible for, but that's the way it is with every other crime as well so what's the point? The concern you're raising is referring to the justice system in general and how trustworthy and reliable it is in its decisions, and not a concern with one specific law or another.
There's no sense in worrying about the radical Islamic ideology becoming more compelling when it is already ridiculously compelling to young European Muslims due to the lack of action that allows it. Actions need to be taken against it, practical actions, actions that lead to actual results and not these empty politicians' promises after every act of terrorism to "fight radicalism" that do nothing to prevent the next attack.
"The darkest places in hell are reserved for those who maintain their neutrality in times of moral crisis."
Perhaps in your next communique with the terrorists you can tell them that following the next US election a coalition will be formed to turn their surroundings into the worlds largest slab of hairy glass.