I wish the whole school was like that, but this particular teacher was more an exception than a rule. The only teacher I still talk to / hang out with (5 years out of graduation), that was the one room where no gay jokes would be ignored.
I think "the cage" was left deliberately vague, because it's like...we're the ones that can see that we're in a hurting world. What those hurts are, and how we see them, and how we think we might go about healing them are going to vary from individual to individual, and I think she saw that and was ok with that and wanted to be supportive of multiple emphases. Queer rights is obviously the direction I settled on, but other folks went into environmentalism for example. So I guess the cage is primarily societal, but there's definite tie-ins to the other things you bring up. I've heard her make reference to the metaphor in a spiritual sense too, so I think it's just an image that she likes that's fairly adaptive. As for leadership roles, I think that's exactly what she meant (though I could expound a bit on wider definitions of "leadership").
I threw the "unsee" part in because I went through a phase where I very literally tried to pretend things weren't all kinds of terrible. Because then I could be happy like everyone else. It doesn't work.