I think he does have a point though in that certain terms are considered racist only at certain periods of time. The meaning of the word gets reappropriated. So if you called someone a negro today I think most people would say that is racist, or at the very least politically incorrect, whereas 80 years ago it was not only considered not racist but actually was the proper term to describe Africans and was used in scholarly works. But eventually it started falling out of favour and now it would be considered racist if you used it. So, the percieved racism of words is entirely dependant on the historical context in which they are used.

This probably doesn't have much to do with Leia, though, as she was clearly angry at Chewie and deliberately talking down to him and everyone else. I still don't see how that would make her speciesist or whatever, even if she may technically be making a comment on his appearance. It's like when Han calls him a "furry oaf". He has lots of hair, it's a distinguishing feature, otherwise if that's speciesist then commenting on any physical trait would be speciest since everyone's physical traits are determined by virtue of their species and are not optional. The Death Star commander, on the other hand, calling Chewie a "thing" is pretty clearly speciesist since he doesn't even acknowledge that wookies are "people" but instead refers to him as an object.