It is a human kicking the ass of a spacesuited-space jockey, which fits with what I said above. It's war with humans. The guy even has a bullet-belt or something.
No it's not look closer. The thing on the right is clearly in one of the engineer space armors (see the neckline, and compare it to the living engineer's neckline of his suit)
If anything it's more like a civil war