I could certainly see Carter being the one that helped attack his home and destroy it. Fits perfectly into his backstory even if he regrets the act.

I did want to make a suggestion about your energy cannon though. [@Cultural Titan]
If it really is able to penetrate armour, wouldn't it be more fair to say a longer recharge or even a single shot system? Energy capacitors would easily burn out in my thoughts of the design, so I could see that being its flaw, which would give it more of a tension build for the whole "One shot one kill" being an emphasis on the one shot. It's up to you, but I just wanted to contribute to ideas.

Just don't put an exhaust port, we all remember Star Wars and Exhaust ports...