There is a term for parents like this: helicopter parents, those who feel the need to hover over their children and micromanage every single thing related to the child's life. That is not healthy for a child whatsoever!
Just because the scenario was one way last year does that mean it will be the same way this year? The stereotyping of "right out of school, single, and with limited experience" is unfair. What if someone's experience with a sahm was that all she did was sit on the couch and feed her kids junk, and then she applied that ONE experience to ALL sahms? Are all sahms lazy? Oh most definitely not (sahm is one of the hardest jobs out there)! But is it fair to categorize one class of people based upon a single observation - most definitely not!
Even more concerning is the comment about him being single. Would the family feel the same way if the teacher were female and single...like a whole bunch of brand new female teachers are? Sounds like a little bit of prejudice to me.
The family needs to be more open-minded. I agree whole-heartedly with many of the previous responders in that they just might be surprised to find that this new teacher has fresh ideas, unbridled enthusiasm. Keep in mind that with the economy the way it is, jobs (even in education) are not as plentiful as they used to be. Sometimes hundreds of teachers are applying for one position, and this allows the school to be more choosy. If this were my child and I had reservations, I'd still have him start off the school year with the assigned teacher. Going through school is not only about academic subjects; it is also about negotiating relationships, learning how to manage conflicts, building positive relationships with teachers and learning to reach out for help and assistance when needed. If this family races in at every opportunity to 'fix' things for their child, then the child learns "mommy and daddy will do my dirty work!".
Give it a chance. It might be the best thing to ever happen to the child. Right now, the family really doesn't have a leg to stand on. "I don't like him" isn't going to cut it, and if they make a change for this child they have to do it for every child, which is not going to happen. If after a few weeks there are some serious (documentable) concerns then there is a case for a possible change.