I am a taku fan and I would say it's a big possibility he wouldn't because if haesoo wouldn't have been in the relationship with his step brother he wouldn't be who he is today. Wouldn't have the mentally he has that he puts in his writing. Remember that taku is a fan of his writing and how he views life because it is similar to his own view on life (this was a character description event done before the first chapter came out all the characters had a description. Just incase you didn't see it)not just the the stepbrother relationship.
Haesoo is cynical and mysterious greatly because Jowoon shaped him that way. I think Taku is a very curious person so he's enticed by the complexity of Haesoo. I definitely think he wouldn't be that interested if Haesoo wasn't so dark
I WROTE SO MUCH MORE BUT IT'S GONE
To be Fair.. Taking has been interested in Haesoo's since the second he saw him the bookstore. I dunno if it's a writing flaw or if the writer planned it? Like I understand love at first sight but it's out of character for someone so weird like Taku no matter what his past is. He looks choosy, but I don't know what his standard is anymore since he hangs out with someone like Leo... And then his pornstar Ex... I think he liked Haesoo at first sight because of his looks and he's not as mysterious as he looks.
but back in the bookstore when he saw haesoo he didn't even know his name ,but he decided to buy the magazine to know more about him ,also when leo showed him a pic of haesoo with joowon he genuinly looked surprised...but still who knows
do you think taku would have been interested in haesoo to this extent if haesoo never had this pseudo-incestuous relationship with his joowon? if haesoo was the same haesoo except he never slept with joown? this is a genuine question btw, im curious. bcos I know haesoo is alluring in general but for someone a bit eccentric like taku, i feel most of the allure is driven by this forbidden relationship he has with joowon