That's simply untrue. The transition from Class S to yuri occurred in erotic josē magazines, not sēnen magazines, in the 90s, especially in Lady's Comic Misuto. Yuri was already a term of community self-identification among lesbians in japan before this going back to its use in the Barazoku magazine in the 70s and 80s. Since then, the development of yuri has occured in lesbian dominated magazines like Yuri Shimai or Comic Yuri Hime, not in sēnen magazines. Yuri is a lesbian genre that sometimes men also enjoy, but this does not mean it's for them.