Well I suspect BD encountered more not directly enthusiastic replies about FF content (like mine that do not want to say no, since some others do love it and it is BD's game plus does not have to be only my preferences, but got worried by the word many) and maybe even more strongly disapproving or worried replies from Patrons. So he wanted to gauge how strong and if that would go for all relations, including a few he wanted included from start and what people would find an acceptable balance between FF and MC content if not great fans of FF content.
Like I would not mind much for Shauna/Jamie or Bailey/Rainn lines even if would avoid the scenes as such, if Wendy, Willow and Azel would have FF scenes shown that I would not be able to enjoy (for my reasons,I could see them ofc but not enjoy them), while never being able to have scenes with MC that I would, I would be at least a little jealous.
To me them having FF scenes would be as annoying as if it was a loving nice guy other dick.
Now I would shrug that off after a little bit, but others would start whining a lot longer and louder likely.