Should displaying an ISIS flag be banned by law?

I have to disagree, i think it should be illegal to honor the flag of an enemy to the united states, or any civilized nation, but i do think there should be an exception made for parody and art in general provided that it is not supportive of said enemy "state" or anything they stand for, and not every isis member is going to make a show of displaying the flag, therefor it would just give people a false sense of security and as such could allow some to slip through the cracks who might have otherwise been reported, remember, the 9/11 hijackers weren't dressed in tunics and/or turbans, they were dressed like us so that we would let our guard down.