A quick clarification on that...! You can definitely accept Kex and enable all bi content.One thing I noticed is that in order to enable one kink you have to skip some content. For instance, if you want to enable bi content, you have to reject that alien lady's advances. I didn't really miss much there but some people might want to see that. Maybe you could make a poll to find out what players like best-forgo some content to enable other content or select all their kinks at the beginning of the game or in game settings.
There are 3 different points to enable bi content. The first is in Medbay (if you fantasise about the Volchak), the second if you reject Kex in the corridor, and the third if you choose to look at Sam's bulge in Decontamination.