Ha yes, the triangle
No, off course, it's not censorship, like I would have to put on the niples if I wanted to post the picture on Facebook
In a sense, it is even almost the opposite, a way to emphasize the most explicit part of the project.
All the concept is based on the inversion of the tale. Here, the bluebeard is a woman (probably killing here many husbands, so). The visual concretization of the concept of inversion is represented by the blue triangle which therefore makes the transformation between blue beard and blue pubis. Also, notice that the triangle is somewhat a symbol of permutations in its capacity to fit in a circle, at the same time fixed positions and turning circle (ok, that's a lot of conceptual considerations with not much interest, just something I had in mind at the begining)
But you're right, it is not very clear since you're already the second person to make this observation.
Perhaps it becomes more obvious with the title wich, in a sense, explains the triangle by its design ?