Maybe it's just me, but why would a station promote something they ARE NOT going to do? Seems counterproductive to me. Just play your format and handle the calls as they come in... but DON'T promote a negative.
Stations could simply play all Christmas beginning at 6am Christmas Eve and continuing Christmas day until, say 7pm. Beginning Christmas music now is just, well, dumb. I don't see the programming reasoning behind doing it this early.
Look at the ratings to see the reason. The station to brand itself "Christmas" first and best in any market gets a nice boost.