Or maybe the problem isn’t the nipple itself, but the context in which it’s shown.
In the meme you posted, the context of the photo on the left is basically sexual assault (one person exposing another without their consent), and the meme itself implies that the (justified) reaction to it is overblown, as if it is comparable to someone willingly exposing themselves.
It is not.
The meme is a really bad take in its own right, and has nothing to do with free the nipple.
How is the meme on the right non consensual? That lady is smiling in the photo and people from Africa are not fucking idiots. They know they're being photographed for National Geographic. She clearly does not give a fuck.
The right one implies consent, the left one doesn't that's why it's wrong because the meme implies that both are similar and thus the reaction to the left was overblown, which is wrong because the context is completely different.
If they're trying to imply Janet Jackson was sexually assaulted over a simple accident that literally happened live on TV that no one could anticipate or stop, then I don't know what to tell them.
Did Janet Jackson ask for the wardrobe malfunction photos to be erased from the internet?