@degenerateafro
Boys may start puberty a little later than girls. Not saying that the girls aren't far into puberty yet.
However, I already pointed out that despite getting flustered by his teacher, he felt nothing the same for the children (especially little Milly).
He does have some desire, but only that of an old man.
> Zeff has shown attraction to Redia well at least her boobs
Boobs are boobs. Attraction to boobs is one of the most common and socially acceptable fetishes. Boobs don't make the person - as the shirt print says, "my eyes are up here".
> Zeff isn't 100% oblivious to inuendo
You're right. He isn't oblivious. He's an old man. But that only supports the idea that he's simply not attracted to children, even if they might be a little precocious.
He may react to their more "adult charms", but as long as they are still children, they, as persons, are not in his strike zone.
It's more of an emotional thing, which greatly affects physical reactions. Even they do manage to get him to pitch a tent, he's not gonna act on it, because as you've said, "physical attraction and mental attraction are separate things".