Personal blogs or not, people in teaching positions are considered teachers and representatives of the schools first, and people second. Just because someone's personal blog is theirs doesn't mean people turn a blind eye to what's written or posted. Privacy settings are there for a reason.

I'm personally sorry that he's been fired, especially as I imagine he's made a huge impact on a lot of young people. However, he had to have an inkling of the consequences if he was "caught." I hope another institution snaps him up quickly for their students.