Am I missing something here, or does the whole iced coffee thing not just amount to the question of whether you should take food or drink to an interview?

If someone brings a half eaten big mac to an interview, that's not creating the best impression. It doesn't suggest they are taking the interview very seriously. Same goes for iced coffee, popcorn, red bull or whatever. You could make the case that some "professionalism" norms are inherently racist (no doubt they are mostly arbitrary rules made up by white men), but I'm at a loss as to how this particular one might be. It is just that we should do away with the whole concept of professionalism and just say anything goes in the workplace? I'm not convinced that would go well.

EDIT: Just for clarity I'm not saying it should be a deal breaker either. Only that you could reasonably expect to make a better impression without an iced coffee than with one.