You can, but I'm not that anonymous (one can easily find my name by searching for my username, not that there's much interesting to find anyway). More importantly, I wouldn't try to damage a person's reputation if I wasn't ready to stand behind what I said and, if proven wrong myself, take some responsibility. I think a few negative things were said about his personality, which can be damaging. An anonymous internet comment is not the most credible source though.

Disclaimer: I don't work for Meta, don't know Carmack, etc.