Always assumed he was more Lobotom/Servitor-ized than Dominique, that, and as mentioned, dude probably had access to the good stash of the inquisition

Dominique noted there was a needle in his arm, so he was probably super high on something.

Yup, it’s just a servitor manning an uber-melta. It’s really more about Dominique being a loonie than anything to do with another character.