nope. I would NOT be happy with this, and although SCHOOL BUSES are safe, this is just a van. No way would I be risking his life everyday.
I would offer to supply the seat. I would offer to purchase a coat to leave AT school so he doesn't have the bulk of carrying it, but I would NOT be allowing both the inappropriate seat (I would want the harness still) OR the coat/BACKPACK
on while they are moving.