As Moc1 will tell you homeschoolers are allowed to play in public or private schools. I believe they can play in ANY private school, but only their zoned public school.
However, I'm not totally sure of this so please check the rule before you act on any decision.
From a source I know, I was told the Olympia baseball coaches did nothing wrong - in fact went out of their way to make sure this player was legal. And they did it as a nice jesture for a good young man.
My guess is that the AD was told that Orange County approved everything and left it at that. From what I understand Orange County DID approve everything, but they never got approval from the FHSAA.
My point is that this was an innocent mistake and the kid will eventually be eligible once he goes before an FHSAA hardship hearing. So why punish the rest of the kids for one adults mistake. And why punish a coach (by forfeiting games) for doing something like helping a young man with his life by bringing him onto the baseball team. He should get positive feedback - not forfeits.
Just my humble opinion. If my guess is wrong please don't crucify me. But my point stays the same. A coach was trying to do something good and got in trouble for it. That's not fair.