Anyhow, MMT is a very popular thing right now, so it's obvious he would get attention regardless of his age, gender or race.
i.e. if you're the only non-white but otherwise fit the part / especially if dressed on the smarter end some people are less likely to question you because they don't want to be seen applying a bias. Actively questioning the one black guy is a lot more obvious than actively not questioning him.
Many people aren't immediately conscious of their biases. This isn't the same situation, but I thought this article about being a black CEO was illuminating. I've seen the similar bias-exposing mistakes happen to women.
https://www.mercurynews.com/2020/06/16/for-black-ceos-in-sil...
They're easy mistakes to make (I made an similar mistake by assuming a young woman was a nurse and not a doctor), but the most important bit is to learn and be aware.
He made a vastly more hurtful claim - that everyone else was 'barred'.
You're simply not responding to the charge that's been made, you've chosen to try to argue a far weaker claim (which is trivially true) instead in the hopes that nobody notices the difference.