What's this got to do with political correctness?
The whole reason for a school uniform (apart from the social levelling mentioned in the article) is that it looks smart. If you're wearing your tie in a way that makes you look untidy, you might as well chuck away the uniform all together.
I don't think this is a great idea though. The only reason I know how to tie a tie is because I spent 5 years doing it in school. I think the risk of tie-related accidents is fairly minimal, so it does seem kind of pointless. That said, I think it's a bit of a minor issue to get fretting about. There are bigger issues with education than the type of tie a kid is wearing.