Nah HE'S the one that's traumatized, been neglected since he was a kid and was starved for love, so when he sees his mother having sex with other people, an act normally associated with 'love', it warped his mentality
Anyways the way that it was show was really unnecessary with him blushing as if he was turned on seeing his own mother having sex, and saying couple times "I wanted her to be looking at me as she does it", it's just weird, don't come with this Freud shit to me
It is weird (haven’t seen the scene yet !) but psychological wise the explanation the person gave is valid and those situations can happen, nothing to do with Freud it’s just the way a child’s brain is wired
Sorry to necropost but! I don't think it was necessarily him thinking his mom was hot, but rather that the fact he wanted to be acknowledged by his mother got messed up-- when seeing his mom be capable of "loving" someone, he wanted for her to look at him too, as it would mean she loved him as well. He was blushing and probably aroused because watching people have sex can do that to you, but not because he was specifically aroused by his mother; this his introduction to "porn", so to speak (iirc Enraku mentions to Shiki that this is how he learnt about sex so...).
All those things combined in a brain still in development, so signals got crossed and it lead to Enraku's NTR kink.
Bro I was liking it until the part where one of the tops says that he wanted her mother to like at him while she was having sex? And he was blushing as seeing his mom fucking as he thought it was hot? Wtf I'm traumatized