As much as I despise the rise in the retirement age, let's not have too much fun at this guy's expense. Joke about senility all you want, but until you've seen it utterly consume a loved one to the point that you don't even recognize their personality anymore you won't understand how painful is can be.
Having said that..... Retire, you old farts!!!
And... having said that... don't make fun of older people. You'll see it in your family one day, and you'll be there one day yourself.