I never said it was going to be about "wrong or right" it just started to seem like more debate about the word "open" .
As far as I know their was never a restriction upon gender and that anyone was allowed as long as they met the pre-req or "qualified"
As per wiki:
Jean Balukas : On August 6, 1978 Balukas became the first woman to qualify to play in the men's division of the World Open Pocket Billiards Championship; a tournament with a 100-year history. This meant that she would be competing in both the women's and men's divisions of the tournament to be held on August 12 of that year at the Biltmore Hotel located at 43rd Street and Madison Avenue in New York City
Balukas was initially entered in both the men's and women's divisions of the 1987 B.C. Classic, a nine-ball competition. After notable controversy (detailed below), she competed only on the men's side. Along the way she trounced Keith McCready 11–3 (at the time the 17th-ranked male player by money list, and who guest-starred as obnoxious hustler "Grady Seasons" in the 1986 film The Color of Money). Balukas finished in a tie for 9th place among many of the best players in the world.
Im sure you already checked wiki
though but this is what I know as well.