Thats not him... lol someone made that up for fun. The masterchiefs face is never actually in the game. In Halo 1 if you remove the longsword at the end its really just him pulling off a helmet from his head but his helmet remains on his head.
I have pictures of the chief putting his halo 2 helmet on from a perspective so you can see he already has his on =p. Its just for props...
-Doom