I don't wanna be in charge of the rainbow pissing ponies.
Truth of the matter is that people still care and it is only a relatively small percentage of people who do not care. Even some of the people who claim not to care have limits on how much they actually want to SEE it. Meaning, some things work in theory but not in practice and people are often not as open and accepting as they've convinced themselves. Inequalities would not be pervasive despite social changes if the world was as peaceful and accepting as the ponies are telling us.
For the record, even supporting rights and pride means we (those of us who are outspoken in support of freedoms) care.

Not caring either way is apathy and that means people have the ability to ignore it either way. So, it does matter to us with whom people are attracted (with or without sexual encounters). We also know that a lesbian sorority member doesn't necessarily want US. I don't want every man in the world and every man doesn't want me. The same applies to women in sororities.
For another record, there is technically an aspect of single-sex GLOs that is also often manifested in single-sex schools. Some people begin to "date" within the group or become curious and exploratory within the group. If that becomes an issue, talk it out and make it clear that this chapter/GLO is not a hump haven.