One of the bi stereotypes / cliches that gets rolled out is that bisexuals are more evolved than other people. Cos, y'know, we see personality not gender or genitals. And by 'see' they mean fancy, or indeed intimately enjoy.
Though that's a worrying definition of bisexual so far as I'm concerned, because I've 'seen' a lot of personalities, a lot of genders and (gasp!) even some genitals as well. Sometimes the gender of the person has been important to me, sometimes it has been important to them; oftentimes not.
It is I'm sure a well-meaning thing to say. It implies a certain "I wish I were, I just don't have it in me", and it's complete nonsense. We're as evolved and as prone to cockwomblery as anyone else.
Earlier I was reading someone (no links, doesn't deserve the traffic) bewailing that they had tried going to bi spaces, but it was just so terribly unwelcoming because they had to listen to women, too.
More evolved? Pffft. In this case: the 1950s called, they miss you and want you back.