I guess my argument would be that you can act as though players are just automata following the dictates of the game design, but I think in truth that's not the case. You kind of have to afford others the same sense of place, time and meaning that one would ascribe to themselves, and that the choices they make as just as informed as your own.
Well, yes, players aren't automatons; that's central to the idea that they can read into game design things the designers never intended. I think the reason they focused on automatic team assignation was that it's one of the areas in which player control
is taken away.
Yes, if you give players any kind of opportunity to do hateful things, some fraction of the player base is always going to do them; teenagers' eagerness to scream various slurs into voice chat is a meme for a reason. However, when those choices are instead imposed as a precondition of playing the game, the players who want to make them are joined by the players who just aren't bothered by them to the point of quitting, and maybe getting people used to seeing Nazi iconography isn't something game designers want to just passively accept.
Now, there's the related argument that maybe we don't want game designers doing that at all, which is I think what some people are reacting negatively to, but that's a bigger problem than just with video games, from our modern neo-Nazi edgelords to the reenactors who enthusiastically wear the uniforms and carry the guns and aim for historical accuracy in every tiny detail except for the ones we might arguably consider the most important -- and there's considerable overlap between the two groups.
I might have a bigger problem with the video and the impulse behind it were the far right not actively, consciously engaged in normalizing extremism in precisely this manner. They want you to look at swastikas and see historicity, to listen torch-bearing mobs chanting racist slogans and hear free speech, to look at our migrant concentration camps and think only that our immigration laws are being duly enforced. They want to create an environment in which you start comparing them to their even more extreme cousins and going "well, they're not as bad as those other guys" because that's a step closer to "well, they're not so bad." They want you to compromise, to be reasonable, to meet in the middle over and over and over again until you take the moral high ground by going with the slightly less enthusiastic Nazis.
Extra Credits was heavy-handed in their messaging, but I think the core idea that we shouldn't normalize extremism by divorcing its appearance from its reality is a good one.