That's a huge factor no doubt. Had the shoe been on the other foot and T'Challa launched a first strike against Latveria I have little doubt there wouldn't be an arc in Fantastic Four or Doom's own book where he gets utter revenge against Wakanda. And I do get the feeling if T'Challa was white this probably wouldn't be as big an issue because they probably wouldn't care as much about him not being "noble" if you know what I mean.
There's this divided perception of T'Challa that he's a simultaneously gritty, take-no-prisoner hero who isn't afraid to step outside moral bounds and this noble, philosopher-king above grey morality. It's why you get a T'Challa that's willing to crash the global economy and starve children in the Priest run then you have T'Challa choosing not to execute Doom despite starting a coup in Wakanda. Writers are selective about the kind of T'Challa they want when it serves their interests to keep a character alive lol.
And I think this speaks to a wider issue of comics not wanting black characters that are too morally ambiguous. Who embrace making tough calls and are willing to break their own moral codes. They always gotta be the voice of reason or the one taking the high ground. T'Challa and Storm funny enough are two characters who I think have lost their edge and willingness to be dirty in recent years.