He has no personality issues and has no bad behavior. My DIL says my son is too busy and not responsible to aid in any care. She does not work but has made it clear this is not her family. She believes my young grandchildren will be confused by Papa's lack of any executive skills. He had EOAD. She has asked my son to take a "break" from us as he needs his family to come first. I don't want to create any marital problems for my son so we have just remained silent and alone.
Your son is afraid to tell you he is traumatized by what he sees. Take that to heart and get professional care for your husband.
Some people are afraid of dementia or any kind of mental disability because they expect the person to suddenly break out with they kind of bizarre behaviour mentioned above and they are often not willing to be educated out of their stereotypical views. Maybe if you arrange for family get togethers at a neutral location such as a kid friendly restaurant, park with a playground or another relative's home they will have the opportunity to see that dementia isn't necessarily as scary as they imagine.
But I think your DIL has her own agenda:
"My DIL says my son is too busy and not responsible to aid in any care. She does not work but has made it clear this is not her family."
That's a very revealing statement. I doubt if she'll ever support you but will try to keep your son away from helping. I don't see a good resolution to this situation.
And given her attitude, I'd follow CWillie's suggestions of get togethers away from your house so your husband can still see the grandchildren but in a neutral setting so hopefully DIL won't act out and scuttle the visit.
God forbid. Right, now I've got that off my chest:
DIL is an ignorant cow. But she is nevertheless your son's wife, and your grandmother's children, and there is nothing to be gained - as you quite rightly appreciate - by entering into any sort of conflict with her. Being as ignorant as she is she may genuinely fear that the children will be confused at best, very frightened at worst, by their grandpa's strange reticence, most especially because their mother is likely incapable of explaining to them what is going on; but I suspect that Pam is right to guess that your son is grieving very badly and DIL wants to get him away from the source of the pain.
Actually, she can't. Because the source of Son's pain is the reality that your poor DH, his father, has been attacked by this evil thing. But DIL doesn't sound like the kind of person who really sits down and thinks things through. Not if she believes that Son will feel better for running away from his family and pretending that this isn't happening.
But you can help your son by giving him permission to do whatever helps him cope best. Talk to him, do your best to set his mind at ease, and meanwhile make arrangements to be well supported in caring for your husband without relying on your son's help.
Does your husband miss your son and his family? Does he ask to see them?
With these statements, it appears to me that she may be a controlling person. My ex was an extremely controlling individual and I can hear him saying the above. I am wondering what your son is saying or does the DIL speak for him? It may be that he is telling her to say these things so that he doesn't need to speak or he is just trying to keep the peace as he has to live with her.
If he isn't speaking up, then I would have to agree with the others, in that, you need to give him space, getting it into your mind that there will be no help from him or, perhaps, seeing the grandchildren.
In my case, my grand-daughter (turned 3, first week in August) spends the night with me every Wednesday. Mom enjoys her visits and GD enjoys them as well. GD includes Mom in all of the activities here, dancing, singing, games, etc., she chooses to help Mom get ready for bed, she watches Mom eat and reminds Mom not to eat her napkin, etc. GD will look at me when Mom says or does something not the norm and I tell her that Old Mam's (that's what GD calls her) mind doesn't work right sometimes. If and when there comes a time when I need to shield her from something Mom is doing I will do that as not to be traumatized GD. Mom hasn't roamed the halls at night, at least not on Wednesday's yet, I think GD wears her out! It helps that GD is a very sound sleeper if that happens. So, far GD doesn't seem to be fazed by anything, perhaps I have an exceptional GD.
What are the symptoms of your husband's EOAD? You specifically mention executive function but that is a huge range of possibilities.
Sounds like your son needs to grow up. No one can control another person unless the person allows them to. Period. The kids are his children too. If your son wants his children to know his grandparents then he needs to make the effort. Why not invite your son and his kids to have lunch at your house where your husband feels most comfortable? Lunch need not be a long affair.
This really is about your son deciding for himself whether or not it's important to him for his kids to have a relationship with his parents. If he doesn't start acting like a father when the kids are still young, it will be too late and your grandchildren will learn all the wrong things from their dad being a wimp.