I didn't call it out for being 'hateful'. I fully acknowledge that it was a joke. I'm just trying to point out that, given the current political climate, it's a really, really bad joke that can easily be read as offensive.
Believe it or not, I was not the one who equated the joke to slavery. Gaia did that all on their own. After speaking to a few American friends who have said that "built on the backs of" is sometimes used in reference to other things, I can see why a lot of people see this as overreacting. I've been taught that that term is almost always followed by 'slaves', or at the very least by 'poor people whose labour was abused'.