This is OP.
Thanks for all the responses. I had no intentions of letting him drive in the snow, but he insisted that I'm the only one who would say no to this. (We do live within a quarter mile of 495, for the PP who mentioned that). Thought I'd show him that I am not the only parent with some common sense.
I did offer to drive him later and pick him up if he wants to go. FWIW, some of the stores at the mall are closed due to the snow--seemed sensible to me.