...because the homeschooler's parents pay in full for their kid's slot at the school, whether he actually does his academics there or not.
But they didn't enroll him at the school, so why should he represent the school over someone who actually goes there? Should he be able to run for Class President too?
I'm wondering if you'd make the same argument if we had a good voucher program. If parents were reimbursed for their property taxes to fund home schooling or private school, would they still demand access to play on the teams of schools their children don't go to?