I think this has been an extremely unpopular theory, in fact I don't think I've ever seen anyone other than myself propose it (tho i always thought it was pretty heavily implied), but Curren has been confirmed transgender
Unlike Scrap Sandayu which takes place in continuity with Kinnikuman or Tatakae Ramenman which could be called a parallel universe, Gourmand-kun is set in the "real world" where Kinnikuman exists as fiction, so it's a natural setting for Chaos who, partly, represents kinniku fans
Gourmand-kun is a manga I love deeply for many reasons and this isn't even the biggest one, but it's owed a place in my heart because it represents the first appearance of Chaos Avenir