Firstly, people probably should not take characters of this author as if they were real close friends whose behavior you are criticizing - like the my teacher is my sex friend in which there are some really deplorable things and really questionable behaviors going on but it's darn funny, which is the point. Point is not to think what will happen to the relationship (or mental health) of the trio when the teacher fucks both mother and daughter.
Secondly, and more importantly, it is always very disappointing and painful to see disdain or even hate towards bisexuality from gay/GL-BL audience. They are not "confused" or "playing around", they like both sides, and that is just as normal as homosexuality (or heterosexuality) is. I get why people do this, since all people think in black and white, my friend or my enemy, but maybe try to think a bit of how much it would piss you off if and when heterosexuals call a gay relationship disgusting or when they call it just pandering and being woke or whatever the fuck is always done as a "response" to small lgbt representation.
Like it would be funny if it WAS just an absurd joke someone made in a comment a while back about "feeling like a touch of dick forever taints your yuri" or something like that.
If you can't change your mindset, avoiding the bisexual tag instead of complaining about the things it represents would be the least thing to do.