Citizenship can be revoked if it can be shown that the naturalized immigrant committed fraud by entering the country and seeking permanent residency/citizenship under false pretenses. Coming here under the pretense of being a law-abiding citizen while actually pursuing a terrorist agenda certainly qualifies as such.
I think it would be hard to prove their intent when they were naturalized. They need to update the law to include terrorism, treason, sedition. Good luck with that getting anything like that though Congress.