Thank goodness there's someone who literally read the chapter's whole narrative, coz it's fucking sickening seeing all these horny ass freaks gooning over the creep old man and all talking about how they didn't mind that old perv getting freaky ignoring that it's literally just the most basic human ethics that stopped him from SA'ing Juhyeok.
Anyways, I'm guessing it's another type of "alpha gender" obsessions within his family like the same case with Yeo Teaju's grandfather in Lowtide in Twighlight where omegas cannot be acknowledged in the family. And I think there's an internal critism about omegas being 'fragile' and not able to do anything which made Juhyeok keeps saying how he hates that system so much, and how he wanna keep proving himself that he's even putting himself in an alpha-dominated sport. Although the only wrong in Juhyeok’s part is how he also projects that insecurity towards Su Ah. I can already see that it's gonna be a messy road for him to be able to fully accept his biology.
The writer has been hinting at something more nefarious and heartbreaking following Juhyeok’s presentation as an omega.
If we go back to the early chapters when his mother throws him that infamous omega party, his aunt came with gifts basically saying "mom and dad decided to not come, but F it I did".
& now in this chapter, Juhyeok drunkenly says that his omeganhood has impacted his mother in a negative way.
It becomes obvious that his new gender dynamic, profoundly changed his (& his mother) relationship with certain family members.
His journey to self acceptance and getting rid of the self hatred, resentment etc… that comes with being an omega, is going to be a long one for him cause how can he love and accept his own self when his own family doesn’t ?