Er no, I know some folks do this. The kids are so quiet, shy and overprotected and they won't know what hit them if/when they end up at university or out working.
Really. My first daughter was home schooled and is now doing very well at uni on a scholarship in the states and has a great social life. There is nothing wrong with it if the social aspect is taken into consideration. Remove social interaction from a kid (who goes to school) in the home environment and you will get the same thing as they won't most likely mix with other kids at school.
As to the OP - "shut up" isn't really that bad - maybe not the best way - I'd say "quieten down" but it sounds like that is not an isolated thing and therefore you should voice your concerns.

