That is not the defintion I think of when I read about Sola Scriptura.

The Bible is the only infallible guide. Not that everything has to be in it. It just cannot conflict with it is the key point. Now this is based upon my classes with people at Liberty and discussion boards and growing up Baptist.
As a United Methodist, the criteria is different.
Now from another perspective, Christmas is commercial for most of America. More Santa Claus than Jesus. I assume, big assumption, that most people are nominal in their practices so they do not get too worked up about it.