I think that depends on how strong the OP’s son is as a candidate, how badly they want to go to Cal Poly, how much they really like the Forest and Fire Sciences major, and how disappointed they’d be if they got locked out of Kinesiology.
As we both know, it’s far easier to swim downstream at Cal Poly for a change of major, making Kinesiology stronger option in that regard. It’s more likely though that they’ll get rejected outright if they choose Kinesiology. Since the Forestry major is projected at 40% give or take depending on yield, it’s unlikely they’ll have space for applicants who choose it as a second choice.
If it were me, I knew I’d be happy with the Forestry major, and I wanted an acceptance to Cal Poly, that’s the one I’d choose.