I don't know. At one point the two may have legitimately shared a laugh about the Jackie title.
I have a feeling Donaldson may have been trying to lighten the mood regarding the hard tag last series by calling him Jackie, but it probably didn't come off how he intended. Then he did it again and it probably came off as distasteful, and then just spiraled. Not saying Tim doesn't have a right to take offense at it, but also not saying Donaldson was intending to belittle him with a racist comment either.
If you look at the altercation between him and Grandal, it definitely looked like Donaldson wasn't trying to antagonize the situation...looked like he was caught off guard and realized what he said was in poor taste and that he just got himself in a load of shit. He then proceeded to strike out on some hanging sliders, which is uncharacteristic of him.
He's got a reputation of being a dick, but I just think he may have chosen some really poor words to try and rectify a situation. I could be wrong, but that's how I'm piecing it together.