Veganism isn’t so much a “dietary preference” as a way of life that recognizes animals as sentient beings and aims to minimize their suffering as much as possible (i.e. it’s not only about not eating them).
That aside: In my experience, giving a shit about the well-being of others, regardless of race or species, isn’t exactly common on the political right.
There are more than 8 billion chickens slaughtered every year in the US alone, to give some perspective.