As for my kid being taught by a Scientologist, I don't want my kid's head being filled with that garbage.
If it's a public school the Scientologist teacher wouldn't be allowed to preach Scientology just as a Christian teacher wouldn't be allowed to preach Christianity. So unless the Scientologist teacher is teaching Scientology you have no grounds for complaint.
Besides, if you have a kid I guarantee that his or her head will be filled with garbage regardless, considering your irrational hatreds and obsessions.