Lowkey, cooking up with that theory.
I also have an inkling that might be the case given the relationships the artists has already created, i.e. alpha x omega, alpha x beta, beta x omega, and so on.
So to do an enigma in this new story seems very likely.
Though, hear me out, it could also be that Siwoo might have had something to do with Byul's idol journey going down the drain since he seems to have liked him for a long time. Therefore, maybe he feelinf guilty about it, resulting in him avoiding everyone as he got older.
Although your theory is much more grounded than mine in my opinion. Still, literally anything can happen in this story. Can't give up on any theories just yet!

1) I wonder if Byul is actually sick and if so- why?
2) I reread the story and I think Siwoo might come out as an enigma. There are multiple instances where he’s crazy strong even for a dominant alpha and even Byul’s dad said something is off with him