Feels like a shoddy explanation, but... alright.
The henchman in question probably died in the blast, anyway. All the better for him. Jack would probably get pissy.
And as for your final comment, I reitirate horngeek's expression:
Well, though he may seem like one sick ****, Jack always does things for a reason. So no, random... ah, let's just stick to 'unspeakable things' are not on his list of things to do.
And yes, according to the community that came up with the concept, Dipsnig, Jack can... do unspeakable things. Weird, amirite?