Not for me to say whether it is or it isn't offensive. I haven't seen the film and I am not someone with "limb difference", which I have to say is a phrase I've never heard before, so I'm not someone this affects directly. I would say that if some people do find it offensive it is not the actress who is responsible for that but the director.
Alex Brooker explained his reasons for saying what he did on the Last leg. Sounds reasonable to me to have the conversation as to why a deformity rather than the claws mentioned in the book.