Oh yeah, you basically read him like a book. He has numerous emotions going on right now, the things that would stand out the most are his current discomfort, as well as his paranoia, stress and general on edgeness. He's not hostile, but he's guarded, and tense, as if he is prepared to retaliate at a moment's notice if things go poorly.
He's wary of Error, indifferent towards Bookworm, and is regarding Hopeless with a small amount of disdain. He has not been making a good impression, suffice it to say.
EDIT:
It's unlikely to be necessary, but just in case this turned out to be an ambush, Jack is wearing his respirator under the bandana covering the lower half of his face, and he's got some of his grenades on him (pepper punch and flash bangs), wirelessly active and running silent, ready to be detonated with a mental command. Hence the leeriness, and being tense and prepared to retaliate.
Should you guys decide to attack him for some insane reason, he'd detonate one in the car. That would end very poorly for all of us, of course, so it's more of a 'I'm taking you with me' strategy than one that would realistically allow him to escape.
Let me know if I need to roll palming or anything, since he's technically concealing weapons. Not sure if anyone is actually searching him for any, though.