Hey Sirius, I spoke to Larry "The Bravo" Ray, the mad genius who designed all of Urgot's chem-tech parts. [sg-miss-fortune]
He said that he imagines Urgot has been evenly bisected, i.e. everything is cut off partway through his torso. However (and this is a bit graphic), his spine continues past where the rest of his torso has been cut off, to connect into the machinery beneath him. This is part of what allows his nervous system to control it.
Part of his belly might also be missing behind the steel plate, his digestive system replaced with machinery. And his arm's loss is his weapon's gain.
That's as official of an answer as we can give, until something actually becomes official!