As I mentioned earlier I have no connection to Thanksgiving at all, so no emotional connection to the foods as such. However, from the OP;
"DH is concerned that our menu isn't traditional enough, and that our parents won't like it. I'm of the opinion that it's our house, our grocery bill, and therefore our menu."
This doesn't sound very hospitable to me. The OP's DH is also hosting this and is concerned that the guests won't enjoy the food. If I had DH's parents over and he expressed doubts that they would enjoy the menu I think it would be churlish to come back with "Tough. We're paying so they'll eat what they're given." I would be absolutely within my rights to say that but I would feel that it was disrespectful to both DH as my co-host and an unwelcoming attitude to guests in my house.
It would indeed be very rude indeed for people to complain about the menu and mean spirited to not come back based on a non-traditional menu. But that particular part of the OP just doesn't sit right with me.
This is what gave me a negative reaction as well - it isn't the menu itself, as who knows, maybe the parents could sit down at that table and be really excited (I would be even though I'd miss some dishes I'm used too & really I don't think it is all that untraditional). But the attitude of my money, my house, my preferences trumping the enjoyment of the guests is not what I consider to be hospitable.
I think I feel strongly about it, because there is such an emphasis in my culture (and others I am sure) to treat the comfort of your guests as the most important thing. Having people over is considered an honor for us and we were always taught to do whatever you could to properly see to a guest's comfort and enjoyment of the food even if it meant that you as a host had to go without. Granted that goes both ways though as it is expected that guests will be gracious in return
So yeah, you can serve anything you like, and they absolutely shouldn't say anything. But personally, I would give people a heads up if I were in this position and change things on the list if I got the sense that they weren't looking forward to the different menu.