One great Supreme Court Justice once said that freedom of speech does not give a person the right to yell fire in a crowed room.

so with the 2nd Amendment do they have the right to branish a weapon in public. Well No they shouldn't it depends on what state you live in and what the corresponding law (if any is),   just like the freedom of speech argument. The only reason to display a firearm at such an event is to instill fear, to intimidate .. all of which has nothing to do with firearm ownership or lawful carry. no honest 2nd Amendment supporting citizen thinks it is ok to do this. A weapon is for hunting, for target shooting, for protection in cases of life and death. The law needs refined and adjusted to deal with this stuff and now. In many states they would be arrested. Again many such displays are not federal violations but state violation and it depends on the state you live it if you even broke a law. Clearly they did not and that is a very sad thing indeed ..