as it was with all predators, Scar included - he was the first to get super opening mandibles, but still in vertical lines with the upper ones, with inner bones going maximum straight forward.
the only creature that had that way of horisontal mouth opening that Tsangs gives every predator was Berserker. wasn't it his first job on predators?
there is this image shown before, of course.
but, as it is not what can be seen in the movie, it's just a behind-the-scenes photo out of character, simply showing what the mechanical head can do.
same as this one doesn't prove that predator uses a human machete
and this one doesn't prove that predator has a detachable head.
so... one time Tsangs uses an actual reference - and it again contradicts everything in the character and thus looks bad.
same was when he likely used a wrong head, not used by P2, to sculpt a P2.