I'm pretty sure bugs are covered under omnivores and carnivores which is plainly what pescatarians are as well. You've given a really good definition, though I admit, I've never heard of eggitarians, sounds like a delightfully British term. I've always heard egg only called ovo-vegetarian, milk only as lacto-vegetarian and missed vegetarians as lacto-ovo vegetarian. Pescatarians just want to feel better about themselves by saying that they only eat one type of meat, which to me isn't really an argument against calling them omnivores if it makes them feel better I don't really see the harm though. For an extreme example you wouldn't say a thief isn't a criminal if they only committed thievery. It's covered by the original term it's busy a more specific form of that term, it's just odd to me.