You're always going to insult some people you deny service to. Not everyone will be offended, and people who are pissing away their troubles will respond particularly badly. You seem to be panicking that you're going to get in trouble because someone assumed you denying people based on legal requirement was because of race. You won't get in trouble so long as you're not letting the white people get away with it. You're the gatekeeper of your own consistency. If you preempt it as a matter of practice, refer to the denial for the inevitable and obvious attempts to loophole around the law, and do so meticulously across the clientele, you won't have any meaningful problem beyond a belligerent drunk. Those happen. Don't try claim that people of color always get to blackmail white people. Just don't be that guy. Seriously.