It is not highjacking to talk about what the holiday is actually about.
Presidents' Day is about presidential history. It is not highjacking Presidents' Day to talk about presidents, even if you ignore all of the mattress sales.
Labor Day is about the Labor movement (I note that you didn't link to the
article you quoted, as it makes that point pretty explicitly). It is not highjacking Labor Day to talk about labor unions, even if you fail to mention the proper season to wear white clothing.