Because he's a kid who rides park.
I'm 200ish, ride a 161. Wouldn't want any shorter, came down from a 163.
Shop in the 155-159 range, depends on the specific model. Lots out there to pick from. Do you ride a lot of switch? If so, find a twin, if not, get something a little more directional.
Expensive trip, right? Spending in the thousands I'm sure. So ask yourself if spending an extra $400 to have the right board is worth it. It is to me...
I love my ns cobra. Quick response, holds on ice/hard pack well, decently stable at speed, and floats in waist deep powder decent enough. Worth a look.