You know, he really can't which sucks. Heck, theres alot of Gundams that can't even kneel because their thighs are to short compared to their legs... these things really only become evident when they are translated to hard plastic instead of "soft" cartoon drawings
Another good example would be Gunbuster crossing his arms.
Haha about the arms I think the right one is okay but whats wrong with the left is that its pulled back under the shoulder and *should* be covered in shadow but i made it out in the open and reflective... doh. I'll have to do a coloring fix and update the pic