I think logically, if the warrior is older than Kane's son, it would be larger, even though the stuntmen in Aliens were much shorter than Badejo (I think the animatronic puppets were a sufficient size, though?). So the artist went by the "film logic" rather than what was really going on.
The warrior does look too big though, as does the praetorian. Brilliant art but they're almost as big as the queen, the latter being pretty much the same size.
