if he gets all the monster girls he'll have to move onto to angel's/ gods then demons, that day will be glorious
and basing in his mentality of treating the monster girls as plain girls, it will be oh so indeed.
this also helps the humans too, since he's gonna be the test case of the scenario "I screwed a (insert species here) and I wonder what the kid will be like" in many ways.
that aside, the government better help the guy in terms of funds since okayado's probably not stopping in turning his house into a monster girl dorm.