I'm going to go out on a limb and say he should be fine, especially if he wore gloves. I used to have to test twice a month for parole and never came up hot from being around it or handling it, or blowing the smoke in my face so I could smell it. Only times I did was at the end, when I actually smoked it because I didn't care cause they really couldn't do anything to me at that point. So yeah, I think he'll be fine as long as he hasn't actually ingested any.
I will add, with prolonged gloveless contact I could see it being possible to accumulate enough on your hands to be absorbed into the skin. I still don't think it would be a high enough concentration to show up though.