Yes it is.
While I think Playtonic made the right decision, they could have removed the advertising with JonTron. JonTron is a douche no question, but just because Home Alone 2 has Trump in doesn't mean I'm going to stop watching it. It would be the their loss if they're boycotting it over that pathetic reason.
Buying a game with a character who's voiced by a dickhead doesn't mean I support his views. Grow up.
I think we get away from the fact that racism is actually hurtful and not just a politically incorrect thing to call out. Just on an emotional level, telling someone that they're diluting your gene pool and that they don't belong sucks. It's upsetting. It's one thing when JonTron insults me based on my skin, but the awful feeling I get when I see the rest of the world ignore it or nod along is on a different level. It's basically telling me that, even if they don't agree with him, they don't care about me or people like me enough to dissociate themselves with a white supremacist.
I think boycotting products that actively advocate, or in this case, would have pretended like it didn't matter, is totally reasonable. Including him in the game would not have been an insignificant action. JonTron is not that goofy guy who does Youtube videos, he's a racist, and knowingly including him in the product is, and should be, alienating. If you're ok with people pretending like he never said the vile things he did, then that's on you, but don't judge me because I won't be part of his normalization.