Which other organizations who didn't kill or committed acts of violence to people in order to be wrongly considered terrorists by the government in the same vein as ISIS was?
>I think you'll agree that this would be a big f*ing problem.
It isn't. In most western democracies, if not all, gaining dual citizenship via naturalization is a voluntary privilege, not a right, that can always be revoked for crimes such as being part of a terrorist group. It's part of the contract you sign when you apply for citizenship. As it should be. That's who the law is targeting.
Your primary citizenship gained via by birth or by descent cannot be taken away from you almost anywhere.