I would think to some extent that any vegan/vegetarian who isn't eating meat because of ethical reasons would have a judgement of meat eaters supporting something that is wrong. Obviously. Not all of them are going to shove their beliefs down everyone's throat but some people are very... pushy, I guess you could say, about their beliefs.
For those that eat those types of diets for other reasons, they could probably care less.
I eat meat. Typically my diet consist mostly of chicken and fish with very little red meat. The majority of what I eat though is veggies. Honestly, I think my diet is probably just as strict and difficult as being vegan or vegetarian because I don't eat processed foods. I don't eat high carb, it's, IMO, not something I do well on. So my pasta consist of veggie noodles. I make my own dressings, still working on my mayo consistency, and pretty much never shop at a grocery store. Local farms are my savoir lol.
As far as the vegan health thing. I don't disagree that it can have immense health benefits but I think that if you're eating white bread and pasta every day that's not going to happen. All natural,( not over processed junk) and real, nutritional food is what's healthy. Regardless of whether or not you eat meat. I do think it's worth noting that carbs and sugars are linked to health problems. Also, sticking to a diet that is extremely low in carbs, a ketogenic diet specifically, has been shown to have immense benefits for those fighting cancer. So, I'm not sure how low carb a vegan can be, in sure it's possible, but from what I've read and personally experienced in my own health since I started eating the way I do... That would probably be the healthiest way to go...