Ah, yes, the famous paranoia of potential queer-baiting (emphasis on "potential") and the equally famous yuri purism. They are some of things the things (emphasis on "some of") that ruin forums the site over. My favourite yuri work, YagaKimi, has several relevant male characters, and you don't see people in that thread finding them "a threat". Paradoxically (well, not really in the eyes of any YagaKimi fans, but it would seem paradoxical to the yuri purists and paranoid yuri fans), Maki actually helped lay the groundwork for the 2 main girls get back together! And that's not even mentioning some yuri manga that have a male protagonist, as a kind of "outside of the relationship" POV, like the brand new 《I'll cheer on my yuri onee-chan》, or the older, but (for some fucking reason) on hiatus series 《Yuri Danshi》. And that's not just for manga, but it extends to manhwa and manhua, too (the Korean and Chinese counterparts to the Japanese manga, respectively). I'm, TBH, yet to read a manhwa, but I did read one yuri manhua: 《Their story》. And, guess what? Male characters that aren't threats, and some that are actually supporting. Saying that all yuri that include male characters are bad because most yuri manga in the distant past used to be what we today may consider queer-bait is like saying that all mappers are shitty because MervueMeringue, the first ever mapper, makes shitty mapping videos. The maths doesn't add up.