Well, I'm pretty sure that the only reason it was brought up in the bio in the first place was to explain Yuri's hair. So I'd agree the statement doesn't necessarily mean contradiction with the in-story setting.
In any case, always great when we get to see author's notes. Pretty interesting that Atsushi got scouted before having actually published yuri, I wonder if publishers find them via pixiv or something. Gotta admit I will be curious to see his thoughts after the conclusion in the second volume, though. For having provided a launch point for brand new yuri mangaka, I'm disappointed all over again about Tsubomi's closure.
Thanks again to YuriProject! The extra material is quite lovely.