It’s constructed in a way that makes it possible to keep Tommy in the dark about who fucked his sister.
When the girls step into the main party room, and get serenaded with the Walk of Shame song, the DIKs don’t actually know from which room they emerged. In the Sage path, when she walked out into the main party room, one of them assumed she’d been with Jacob, not Tremolo. Logistically this makes no sense—to go out that door from Jacob’s room, you have to go down the stairs, through the kitchen, and down the right hall; the faster route goes past the guys on the balcony. And Jacob has other interests, like that blonde girl he fucked after the HOT party (who was there that night), or Zoey; whereas in that path Tremolo had been seen with Sage most of the night. But yeah, whatever, Jacob.
Okay, back to the Maya/Josy path. Tommy saw the MC make out with Maya (and encouraged him to squeeze her tits), so he’d likely assume that’s who fucked her. But it wouldn’t yet be clear to him whom Josy fucked. He wouldn’t automatically presume she had a threesome with Maya and the MC. All he’d know is a DIK fucked his sister—after he had explicitly told the MC to cockblock her.
The other DIKs already know about Josy, and they’re not likely to cover for Tremolo much longer. But yeah, it’s possible for Tommy to fly into a rage, make a few death threats, storm off, and still not know. Thus dragging out the drama for another episode or two.
I don't know... That would be a big surprise. But even if Neil wasn't Fuckface's biological father I'd like that nothing changed between father and son. He's a loving father and that's what counts. Besides, IMHO one of the latent themes present in the game is that in the end being related by blood is not the only factor to consider people family. The very introductory narrative speech of the MC at the beginning of the game speaks about that.
