OP. I admire that you are trying to resolve this.
Its clear from some responses on your thread that some wouldn't.
Your words sound as if you feel you are in a blackmail situation.
i.e. you can't act because of his repercussions.
You are beholden to him.
He is a 75 yr old who should know better telling a 24 yr old family member that she should fuck her far older uncle!
What would be the repercussions for that exactly?
There is a vast difference between you disagreeing with some of his bigotted views (you mentioned), and managing his actual sexual harrassment of your dsd and showing her its wholly unacceptable.
I also don't think its worth getting into arguments with ignorant bigots, and not just because of wanting to avoid any nuclear fallout.
This isn't that. You sound scared to act for fear of his consequences, i.e. him punishing you for daring to be unhappy about his sexual harassment of your dsd!
Bless her, excluding herself from her own Christmas!
I would be utterly floored if my dm accepted that as an option. Horrified that my discomfort around a creepy old man who spoke to me in a asexually harrassing way, meant I had to lose my family Christmas.
I might not want to cause a fuss, but I would expect my dm to be as furious about it as I was - and you are, but just not doing anything about that directly to your father.
I would say, no, you keep your seat at the Christmas dinner table, don't leave. He's the one in the wrong here, andnit wouldn't be a private word, we could all be adults and support those that haven't done wrong.
Buy her a holiday, yes, but not Christmas, that alters nothing...perhaps your conscience. It doesn't give her a great message either.
I would want to raise it as a family all together when they arrive. So before Christmas. All meet up and have it out, face to face, because huge offence and upset and discomfort has been caused, not to mention sexual boundaries crossed.
Why shouldn't he have consequences for this rather than you fear consequences of speaking about it...because its not worth it?
At least if you are all face to face it can be clear what words have been used. DSD will face the one who sexually harrassed her, hopefully shes not too scared now to ever speak with him?
She will get eh opportunity to speak out about what he's done, and learn that this is the way to go, not hide everything away, but use the family support.
Maybe she already knew he wouldn't be confronted over this and so felt powerless to do anything but have to exclude herself from her family Christmas.
Everyone else tiptoes around the aggressor.
This is why aggressors continue.