You're just stupid.
Nanu isn't an old dude, he's just tired and depressed, he's certainly not old enough to be Guzma's father, I'd wager they're within 10 years of each other. Also
>>30172942. Go into that house in postgame and Guzma is hanging out.
Nanu likely let Guzma run wild because he got smacked around by the strongest Bug type trainer in the region, also Nanu doesn't seem like the type to put up too much of a fight anyways.
