One question - Did these venues refuse to display our flags and play our anthem when they displayed other flags and played their anthems. Serious question.
I believe that the original post said that the Mexican flag stood alone. That is not acceptable on US soil. Any foreign flag in a formal setting, to include all government buildings, should be places so it is lower than the accompanying US flag.The Mexican flag was put up there to be honored above our flag. That's what the rules say.