I feel they do know yet emotionally/ mentally they have regressed in age and really don't know what to do about it so they act like children which they are now. We are not dealing with the grown men we once knew, or thought we knew now.
This may be hard to hear yet if they are children and have gone back in time in their mind, it would not be a stretch to say they really don't remember their children now either.
They are being forced to heal their childhood issues which they avoided their entire life which is why they have regressed.