No he's right; racists famously stop making ridiculous arguments when you try and appease them. They should stop waving Mexican flags because it gives the racists ammunition. They should also not speak Spanish because it also gives racists ammunition. You should also probably dress strictly like an American with nothing that might indicate Mexican culture because that gives racists ammunition. You should probably also not invite your Hispanic friends because it gives racists ammunition. You also shouldn't bring up ICE detaining and deporting people cause it gives racists ammunition.
Actually maybe just stay home and just feel really strongly about it? Racists won't find out about it and they can't prove you're feeling strongly about it so there's no ammunition there.