Hillbilly Prince,
I've heard of the book but never read it. Well hopefully you can get your dad on the road to recovery and as you say interaction with others is a good start.
Well let's face it even though a lot of people wish they won the lottery, inherited a big whack of money, etc....so they wouldn't have to work. That's not the solution no matter our age, financial situation, etc....we all need a reason/purpose to get out of bed in the morning.
Don't know about your area but a lot of places have walking clubs for the elderly, social centers, etc....or even him taking a walk in the morning to the local coffee hang out might be a good start.