The message from PETA is quite simple, logical and quite unremarkable, whether you agree with it or not.
Why normalise the wearing of animal fur in the minds of impressionable people when you don’t need to.
Vikings et al did wear fur but no one is suggesting you make unhistorical figures. They are saying don’t create a mythic universe where the ‘good guys’ wear the furs of dead animals.
They aren’t suggesting kids will see these figures and skin the neighbour’s cat. They are saying they will grow up thinking it is cool and acceptable to wear furs. They don’t want that to happen.