It sounds right to me. It just depends, did you mention that "A" is a male in a previous sentence? If you know the gender of the person you're referring to, and how many of them there are, you use his/her/their accordingly. So if you said earlier who "A" is, then your gender pronoun would reflect that in this sentence. But if you aren't sure of the gender, it gets a little too formal, in my opinion: if you know it's singular, you would put "his/her" or "his or her", but if it's plural, you put "their." I personally don't like using "his or her" a million times, so I tend to just say "his," even though that might be technically politically incorrect, or "their," even if that might be technically grammatically incorrect. It's your call how you use it, though, because obviously you're gonna speak differently in an essay than you do in a casual conversation. On that note, what did A have to say about Koreans? (Is A an American? We tend to be good at stigmatizing on our own terms).

How about "denigrated all XXs at his leisure"? Or "to suit his own narrow worldview"?

Here is my answer for your other post:) "He stigmatised all the people in the community conveniently on his own terms." He characterized his community's people as disgraceful or ignominious, by what he thought of them. (shame of what he thought of them)

That sentence is correct and you are using "on his terms" correctly. Although, I'm American, so I spell it "stigmatized". ;)