Um, I don’t think Bart was anything close to resembling a DEI hire or even affirmative action. Bart was chosen because he was seen as an almost guaranteed failure as the town would unanimously reject him for being black and decide to leave town, allowing Hedley Lamarr and his goons to scoop up Rock Ridge for pennies on the dollar for their railroad (due to the quicksand they encountered at the very beginning of the movie). They nearly did reject him in the beginning, only to start warming up to him once he showed an effective prowess at dealing with all the curveballs Lamarr threw at him (ie Mongo). They promoted the idea of Bart as a progressive choice on the surface (dare I say, a cabinet post!), but the underlying reason was to play on the citizens of Rock Ridge’s racism and coerce them to leave town.

So I’d say that maybe it was meant to be seen as an inclusive and progressive choice (in modern parlance), but the underlying reason was anything but (in the context of the movie).