I work IT in a large sporting venue. We get sued for everything. Slip and falls. Fans getting hit in the stands with whatever. Literally, drunks falling down stairs. People who OD'ed sue our care center. A surprising number succeed.
One angle in this case may be negligence in maintaining the Gun Free zone they had signage up for.
“We get sued for everything. Slip and falls. Fans getting hit in the stands with whatever. Literally, drunks falling down stairs.”
Fun place you have there.