That, I find extremely hard to believe.
True, his main selling point was blue girls. It's been ages since he's had a blue girl.
There's a difference between passion and affinity, his main selling point as an author is drawing big tits, and as MalevolentBacon said, of the blue variety, which helped him to distinguish himself from the rest
And he did enjoyed it and he has great affinity to, but he was never really passionate about, it was and is something that he does just to pay the bills, which is why it took him till this very year to release a proper hentai manga, 130+ pages long "完全同意型性風俗♥SS株式会社", after years of people begin him to just draw porn
Fans must understand that Zuygoya was really antagonistic to going into that route, even for the fanbox snuff, it took him well years to finally move from teasing, into softcore porn, into finally like a couple years ago finally drawing nipples (people even started wondering if maybe he just didn't knew how to draw nipples), and then just making one page hentai, and then growing from there
It was a really slow process that took a lot of social pressure from his patrons for him to cave in
And now that he has that out of the way, defeated, and finally biting the bullet (because i am sure he would have preferred getting financial success by going mainstream, instead of going into hentai), he is now free to focus on what he really enjoys, but maybe is not as good at, and is definitively not giving him any money, which is these drama shenanigans that he always shoves in on his series after he comes back to them, IF he decides to go back to them
By comparison, his new and first proper hentai book sold 3k copies first week, and i think they were just pre-orders, which i imagine must give him a lot of conflicting feelings, he has become successful with the one thing he really didn't want to do
Another thing to understand about Zuygoya is that he is a married man and father of 2 kids, so chances are that also played a big role on him not wanting to become a fulltime hentai author
So does he like big tits? yes, but he never really loved them that much, and did try hard to not have them be the main focus, but the man had bills to pay, and a family to feed, plus he did buy a new house too, so you gotta do what you gotta do