For something like this, if you're looking for an easier solution for him, I would suggest the Amazon Fire Stick. This is another connected device, similar to using the iPad and Apple TV, but the Amazon Fire has a built in SlingPlayer, so all he would need to do would be to log in (this also comes with a physical remote to control the virtual remote settings on the TV) after he downloaded the application.
This really does depend on how comfortable you think he would be with the product though, since I know you mentioned he isn't as tech savvy as he use to be. In the end, it may be that the Mac Mini to TV may be what is best for him, but it would be something to try.
I hope this helps!!