Ok, I'll answer but you better keep your word and answer my question.
No, he isn't racist, he might be wrong though. We have several possibilities here. The jurors may have been biased, but he might have also been guilty. Maybe the jurors would have given a guilty verdict whether he was guilty or not, but it just happened in this case he was guilty.
Or, maybe the jurors weren't biased at all, they just happen to see the evidence and rightly agree he was guilty. In that case, the black guy is wrong that the jurors were biased, but he isn't racist for claiming that they were, he is just wrong because they weren't in fact biased for those reasons.
On top of being wrong, he would also be dishonest and disingenuous for claiming the jurors were biased for giving a guilty verdict when he knew he was guilty. But it still doesn't make him racist.
Trump says he loves Mexicans. I hear his hotel makes great taco bowls.