Neither do I, but I know enough to realize that they felt confident enough to say what they said, believing that there would be no repercussions for saying it. That's not an option so they should be charged and convicted in the local British Courts.
There was a case recently in Newry in which a man was jailed for comments that were made online, so if they aren't charged and convicted for anti-social behavior, and incitement to murder, it looks like they have a license to say what they want.
I doubt the family of the 3 Quinn children murdered by a petrol bomb in a sectarian attack, not too far from the Free Derry Museum, were concerned about the sobriety of the people who carried out the attack. They weren't that drunk so that won't wash as an excuse, for that level of anti-social behavior.