Thing is, the conversation starts with the premise that a 24 year old sleeping with a 16 year old (assuming they slept together, rather than just starting to flirt, at that point) is equivalent to child molestation (not a premise that I agree with, but the premise the characters are giving us with 'how was what we did different?') - how 'consensual' it all was...doesn't matter. It'd still be molestation.
'I love him/her' wouldn't make molestation OK. I'm sure, when taken out of the context of being compared to a pedophile ring, these two are a perfectly wonderful couple...but the comparison is being made on the page, and the difference being presented as 'I loved you', not 'you were young, but still sexually mature' is just...icky.
The 'gay molester' implications, knowing Moore, comes entirely from the out of context aspect, which tempers the cringing at that aspect, but it's still a bit twitch-inducing while drawn out of context like that.