Not sayin Evan isn't a lolicon, totally may be, but I'd also imagine that it's much easier, and far more likely to succeed, in changing their way of thinking to foster better human-demon relations at a younger age, rather than trying the same thing with a fully 'mature' demon, who, given everything we've seen, would like have already harmed/killed some humans, if they've reached 'adulthood' or whatever.
....
Not exactly all that much different from 'grooming' now that I've said it...
Still, not necessarily for ill intent either way in this case...