Dear Fashionista,
I am here to tell you, that you can wear white after labor day. The thing about this "rule" is that in fashion, there is truly no such thing as rules. Rules in fashion are meant to be broken, defied, pushed, and even bend. I mean who can tell you what you can and can not wear? Strangely, this "rule" has been followed for many years. It became so important that now, if a celebrity wears white after labor day, an article appears online highlighting the crime that the celebrity committed. The only thing is, the article is written in a way that celebrates them.
But who cares?! It's not like the fashion police will actually walk up to you and arrest you. Wear that white sweater, or those white jeans, or even those white sneakers. Just be cautious of the muddy grounds from the snow, and the dirty winter cars. But hey, no one can you tell you what to do, and just like what i am told, you will do what you what to anyways.