I don't mind them using political views and xenophobia to get heat. Even if they cross the line into racism, it is a character that is supposed to be hated.
But it doesn't really seem to be a way to generate cheap heat, but an integral part of the start of a potentially rich storyline and characters. This way, Del Rio is overcoming more than just a challenger who wants some gold, he is overcoming racism, xenophobia, and (hopefully by mania) abject hatred from Swagger and Coulter. They sound like the elements of a particularly good story, if done correctly.
Everyone vocally hates a racist, either legitimately, like most, or to avoid scorn from other, like a tiny minority. This way the hero is overcoming something a large part of the audience can relate to, rather than a large man who wants his championship back. Even a a large man who wants to hurt you is something the audience cannot latch onto or empathize with as much as is possible with this storyline.