I won't dive into whether the people making the decision were marxists (this whole thing seems more aligned with fascist ideology, frankly), but IMO this had more to do with personal vendettas and petty rivalries between coaches. Coach Propst is not exactly the most popular guy in the Georgia HS coaching fraternity, and a lot of people want to see him fail.
The whole thing feels like a hit job on Coach Propst by the GHSA and the coaches who levied complaint. And if a kid from California gets caught up in it and loses his senior year of eligibility, then that's just acceptable collateral damage to them. He's not "one of us" anyway.
I'm no fan of Rush Propst, but endangering a kid's future and taking away HS football from him during his senior year is a pathetic and embarrassing move. The adults making that decision should all be ashamed of themselves, but I doubt they are capable of it.