I guess the old man wants eris? The succubus will get out and all the women will chase shiki but he is a man on a mission who will never wet his dick because he wouldn't be able to stop wetting it and this is how they keep lewdety to near 0
I love that the MC is well aware that he is a hypocrite. "Yeah, I want a harem. Sure I'm a scumbag, but what of it". Self-awareness is something many MCs lack.