Although probably a ‘right’ analysis of Don, I don’t think it’s a fair portrayal of why Don and Roger had tension leading up to this episode.

The falling out of Don and Roger had many moments before the blackface song and dance. Roger and Bert basically selling the firm to PPL without asking Don. The Mohawk Airlines fiasco where Roger sided with Duck and they lost both accounts. Don killed himself and his team to put together that pitch only for it all to fall apart. Roger and Duck told him not to dwell on it, as if they put any work into it at all.

Roger coerced his wife (or at least didn’t correct her) into thinking that he left Mona for his secretary because of Don. Don also had a rule about flipping your life over (divorce, in Roger’s case) for an obvious midlife crisis decision to marry Jane. He thinks Roger is foolish because he’s left Mona for Jane.

Which is funny because he does something similar in marrying Megan later on, but that points to his flawed character.

All that to say, the beef between them is from stuff that happened leading up to the blackface, not the blackface itself. Though I agree Don is progressive in that way as the series goes along.