So he's "making" $7800/mo, before any maintenance and upgrades? I'm assuming with a condo, the HOA is responsible for much of that, but just how much varies by association. And even if they cover more than most (to includ roofs, painting, etc.), he is still the one who buys a new fridge when the old one dies, repairs the a/c (probably), pays for a plumber when the toilet won't stop running (most tenants won't do even basic repairs), etc. Nor does that include any slush for periods of vacancy.
You mention AirBNB. Not sure if that would be if you buy it, or for your dad. But you need to be aware that AirBNB is a *ton* more work than traditional landlording, and profits aren't always much higher, especially if you aren't in a heavy tourist area. You certainly get more per day, but your vacancy days are far more. And every time a guest leaves, the property has to be cleaned (perhaps covered by the AirBnB cleaning fee) and re set up again. Google for blogs about the experience of running one of these before you consider that a moment longer, and know that if you are talking about for your dad, since he's already unhappy with managing a property, this moves him in the opposite direction of where he wants to be.