I agree it's lame what he's setup but you can't claim that it isn't 100% voluntary.
Even if you have to fill out an affadavit you can.. and if you can list religious or other reasons then they can't deny you.
Therefore you can't get out of it with 100% certainty.
While better than nothing, I still find that option unacceptable. No matter how it is construed it still places the burden to opt out ENTIRELY on the parent. Parents should not have to go begging to the government simply to exercise a basic right about the upbringing of their children.
So, have you ever tried to opt out of a vaccine with your child? Lots of people say opting out is easy. Not one on this thread who's made that claim has answered that question.