brandnew, your Dad is at an age where he's probably starting to realize that this whole Armageddon deal is a non-starter and that he is very likely going to die. My Dad realized that too, about 5 years ago. Time for your Pops to have a little fun. The rebel in him is coming out. Way to go Pops!
The whole dementia/Alzheimer's thing makes any religious person a sinner because they do things that are either against social norms/morals, dangerous/harmful, or illegal as the rational, logical part of the brain is breaking down. I know... my Dad was the same.
Edited to add: If he has dementia, wait 'til he walks around naked in front of you for the first time (unless he's done this before when you and he were a lot younger). That was a real shocker for me! My Dad's urinating and spitting on my carpet and floor was another one. I could go on... but everyone has other things to do.