In fact, it was very deep. it was a satire, and things you have mentioned made sense. Yes, dude got blasted, same dude that shot all these people coldly, gets slow-mo blast to the chest. Thing is, he knew they weren't walking out of there. He could have shook dudes hand and kept it moving, but he was too much of a man for that. The way i saw it, as a foreigner myself, was that Tarantino was looking at America through the eyes of a foreigner who wasn't as familiar with slavery as Americans (Germany, like Russia, wasn't involved in African slave trade as widely, one of the reasons why they lacked wealth with colonies, unlike France and England, sliding Germany down the financial slope, lack of which basically being the reason behind WWI). He saw America fir what it was: brutal, uncivilized and ignorant. That is why he found slavery off-putting,why he brought the whole D'artanian speach, to show Candie how ignorant and uneducated he really was. He made a fool out of him, subtly sliding that line in french (i forget exactly what he said), when Candies lawyer told him that he doesn't speak french and it embarrasses him. That besides all the riches, all his wealth, he was a dummy. And he embarrassed him. That's why Candie wanted to shake his hand, because he wanted to belittle him. So I completely understand why he went out that way. he wasn't thinking of retaliation, he was thinking of his morals that he never bent. He was a joker, but you see that he never went back on his words. It was evident wen he tried to calm Django down during their ride to Candyland and Django called him out. He had no problem admitting it. I personally saw it as a very deep message, at least it rang true with me. The music, specifically rick ross song, were on point. It painted pictures. That sng specifically was supposed to make you look at "black culture" then and where it is now.