I choose to believe that's just trolling social media. Tess is strictly dickly.
If Tess had any sexual interest in women, she would have displayed it all along. She would have had at least one known girlfriend, as far back as her Seattle days. The scenes she's been part of not only wouldn't have had any problem with her being an out-and-proud bisexual; they would have celebrated her for it.
Olli and Tess are both Cluster Bs, which means they each behave in provocative ways to get what they want. Olli strikes me as a Borderliner (and may have admitted she's one; I don't remember). Tess is a somatic Narcissist, which means she is is obsessed with her body, her image/appearance, and being seen as beautiful and sexually desirable. Among the people she most wants to impress, she believes that being seen as sexually adventurous and engaging in "queer" sex (with another woman, who is pretending to be a man) projects the right kind of image.
She doesn't have to engage in non-hetero, non-monogamous, mildly kinky sex acts with "queer" people; she only has to be perceived as the sort of person who does. Whether anybody actually desires her or not (or in the way she wants to be desired) is nearly irrelevant; Narcissists put a huge amount of energy into image management, and to them, being perceived as someone who is desired is almost as good as actually being desired.
Tess needs to be able to claim some sort of marginalized identity in order to not be just another progressive straight white woman (a despised class, even among progs), and since hardly anybody takes fatness seriously, she's latched on to "queerness," and occasionally, half-assedly performs it. But in reality? She's all about the D (but no dick-havers, especially ones she could brag about, are interested).
