Nothing in the Purim Torah guidelines mentions that they need to be otherwise on topic. This could either be because it is obvious that it needs to be on topic, or because it doesn't actually need to be on topic.
For example, this question squirmed its way in to being about Judaism using the oldest trick in the book. Had the OP left out the neder part and just asked it as a clever question about a commercial jingle, would it still be on topic for Purim Torah?
Colloquially, Purim Torah is often not directly about Torah. It sometimes applies talmudic style thought or discussion to completely mundane things, such as nursery rhymes or folk sayings. Is this allowed on Mi Yodeya?