I think of it as how some people’s favorite characters are young anime characters for example killua.. but idk
In this specific case I think it's just poor writing, Iori has no other memories of chika other than when they were young so the grown up Iori seems like they are hyper focused on child chika, but we do see him fantasize about what a grown up Chika would be like in the first chap. So it might be safe to say the author wasn't trying to promote weird child idol inclinations....but this is BL....
I agree with the child idol thing, I really wish that would stop there's really no need.
Ok but why is no one talking about how weird it is that uke is a teenager still obsessing over a literal CHILD idol
And why are child idols even a thing in the first place??