I think there's a substantial demand, if there is no market then we can just assume that it's not profitable for whatever reason. Mr fuckmyface has brought a good point, any American studio would be at risk of prosecution due to subjectivity of the obscenity law.
Also, to us "gay porn" is a huge market, but in the eyes of big studios it is simply a niche, anything that increases production value will be avoided unless the return is guaranteed.
If you go to a more fetish-centered platform like Thisvid, you'll see that there are plenty of scat content being made by independent producers, sometimes not even for profit. The fact that communities like thisvid can thrive around scat and other tabboo kinks is proof that there's demand and it can be profitable.
Other gay private trackers don't even allow scat at all, and here it is a hidden category. In an environment where you need to share more than you obtain, focusing on a category that 90% of the members won't even know exist is not viable.
