never put yourself in competition with someone's mom. maybe there is more to the story than you shared...but it sounds like he wants to take his mom up on the offer to have T-day at her place and he wants to do the turkey and the whole nine yards over there. and he extended the offer to you to go and stay as long as you wish and leave when you wish.
my daughter and her bf have out of town plans for T-day and we have a dog recovering from reconstructive knee surgery and our house is basically on quarantine. just how it is this year....we don't HAVE to buy into any specific plans or traditions just cuz it's a holiday.