I think you're onto something. Kirio's first plan was infiltrating the school. Only when his plan was foiled, they chooses an indirect method.
Remember Orobas Coco during the Harvest Festival? He was manipulated by Ocho, Baal's underling.
And when he was found out, they send Atori and Shiida...
Let's not forget that Akane-mama had to inform Sou-kun through the news abot the case where 2 highschool girl kidnapped a middle-aged man for their own pleasures.
And the reason why we haven't seen these extreme women before is thanks to Satou family and the Guards constant presences near Satou.
In R-18 version, he Nelson'd Kaede easily. Kaede is 46 kg, while Sumire is 57 kg.
The heaviest girl on so far are Akane-mama, at 60kg.
So, Sou-kun can't just princess carry them, but Nelson them too if he wants to.
Nope, all in on Charisma while also building up his Strength and Stamina
In this version, as this is his first playthrough, he's playing the pacifist route. His NG+ playthrough is in the R-18 route