...No democracy, worth the name, denies those who may advocate it's downfall a voice if they are legitimately elected. The UK did not deny Sinn Fein their seats in Parliament, for example.
The UK is not surrounded by sworn mortal enemy populations within easy driving distance of its interior.
The US is not surrounded by sworn mortal enemy populations within easy driving distance of its interior.
Your example of Sinn Fein is largely irrelevant given that it posed no existential danger to People and Crown.
Very few pro-Israel types are applauding such suppression, in this instance.
Merely saying that it is understandable, given the rattlesnake-in-the-crib metaphor; they are obliged to serve-up an occasional limitation that we find objectionable.
Shit happens... that's the way they have to roll, in their part of the world.