You're approaching this as the audience member. I'm approaching this with my graphic designers/artist perspective.

In my position when making art the ambiguity of the message has to be minimal. (I make art for education) if this were an ad for feminism it fails because a big enough percentage of the audience can be confused about what the message could be. If I make art where I need to communicate that 2+2=4 then I cannot leave room for interpretation that 2+2 might = 6

That isn't saying your interpretation is wrong. It's saying there's enough wiggle room to the meaning that if the artist is dead set on most of her audience walking away with the message that "Feminism is not a dial, it cannot be dialed down" then she was not successful. That is dependant on the goal of the artist.

If her goal is to leave it an open question, she succeeded.