Begs the question that public school PE teachers are qualified to conduct yoga sessions.
Probably it would be interesting to see who exactly wants to teach yoga in public schools, what qualifications they possess, and whether they're committed to a dispassionate, non-mystical curriculum of stretching and breathing.
Honestly I think yoga in public schools would be bad for yoga. Like all of those books that are required reading, and generations of students graduate with a deep hatred of those books.
The last thing the practice of yoga needs is high school gym teachers trying to make kids do it right. You wanna do yoga, or have your kids do yoga? Find a yogi that fits your personality and outlook, and have at it. Leave those poor public school kids and their PE teachers alone. Dodgeball is already bad enough, don't you think?