Advent is also a penitential season, but I doubt Bushie or his church will be giving that much thought.
Advent and Christmas are the same seasons. By celebrating Advent, we are celebrating Christmas and vice-versa. It's like Lent and Easter, they are one in the same. You're right, though, Southern Baptists don't generally celebrate either Advent or Lent. It doesn't make us wrong.
Celebrating Christmas without Advent and Easter without Lent is celebrating the feast without the fast, it's like the Resurrection without the Cross, the birth without the labor, and the victory without the battle. Not to pick on you in particular Bushie since you're far from the only one who sees it this way, but how are we going to build a Christian culture of virtue upon self-denial if we throw out all the parts of Christianity that deal with that?