Per the internet both will have thanksgiving dinner. For Biergarten I would expect there to be turkey and some fixin's in addition to the regular menu. I would not be surprised if WCC swapped out the bbq AYCTE platter for a traditional thanksgiving one.
I'm not a huge fan of WCC but I'd probably pick that for a low key thanksgiving dinner at my resort.
I'm guessing that both of these might be available because they are generally some of the last to book up. It's not like the OP is trying to book LTT or something
a friend of mine booked a thanksgiving trip starting a few weeks ago and got ADRs for her whole trip.