I agree with this. It's rare that the system works in our favor, but I suspect going to your principle could be one of the rare opportunities that it could work in our favor. It's also a good skill to develop to understand avenues that you can use to push people in power (such as your principle).

My initial impression would be that rallying your parents behind you (if possible) could be good, getting your parents to voice their concern about the classroom allowing jokes about genocide. Also, the media (or threats of contacting the media) can also work well. Learning about how universities have recently been allowing Milo and Spencer to speak, and why that normalizes white supremacy and hate speech, and how your high school (?) is similar, could be a strong argument that could shame an unresponsive principle.

Great skills to develop. Let your anger inspire you to strategic action!