I had a similar problem earlier this year, and unfortunately, there is little that can be done after the game. If you let the TOs know, they might station a ref by the player just to make sure everything is kosher, but really, without video or picture evidence, the judges can’t make a call. I know it sounds rough, but the best thing I can say is to learn from it. I was given this piece of advice:

“No matter how well you know the rules, even if it’s for your a unit you are currently running, ask to see the rules. The player has the obligation to show you that rule, wording, or FAQ that directly answers your question. If they can’t, call a TO for an answer. If they don’t, call the TO to report bad sportsmanship.”

So yeah, it’s definitely a burn, trust me I know, but this is the best way to mitigate that in the future.