That would honestly surprise me. I'd feel cheated a little bit if I couldn't get a lesbian relationship with Holly because of that, given that she admits to having had romantic interest in women before.
I'm simply making the observation that, in order to get an approval point with Holly in that scene, it also feeds into her desire to become more like Lena. Not saying she hasn't had lesbian feelings before, but to successfully bring Lena/Holly together, the scene at the Sex Shop seems to suggest she needs to change her personality in the long run.
They are not really used for much yet, but Holly has 2 non-standard variables (she also has 2 standard ones measuring affection and romantic interest from Ian/Lena).
I did notice the 'encourage_Holly' variable, however, I think it's going to end up being a Jessica situation from GGGB, where Holly job/profession by the end will be affected by how confident she is in herself and her writing. I don't think she'll stop writing in either situation, just that a confident Holly might make the switch to writing full time because she and others believe in her.
From what I can see, it's 'holly_change' that seems more likely to affect what relationships she can and will engage in.