Unless I miss my bet, the show rules likely prohibited alcohol in any form in the show, and the rule likely was a rule of the venue.The liability insurance may have been contingent on this rule being strictly enforced.No promoter or venue owner can permit activities that can void their insurance.The key here is that there was a "heated exchange", so already alcohol seemed to be affecting the actions of those involved.They may have been given the chance to remove the alcohol and reacted in a less than acceptable manner.
Mike