I'm a vegan and I try to be respectful to non-vegans and their choices but moral decisions implicitly contain moral judgements. If I think eating animals is wrong and you eat animals there is no way around me thinking that you are doing something wrong. I don't need to harangue you about it, which in any case is not at all effective as a method of persuasion, but usually I don't need to for people not to like it. I expect most of the anger towards vegans is because of that implicit (and to be fair in the case of some vegans explicit) moral judgement.