You would probably be ok taking that approach as long as you are acting within your district policies and instructions. The rapport you have with your kids, their parents, etc. is important too in making sure your meaning isn’t misconstrued.

If an angry parent were to take issue with it there is only thing I could imagine would be the question, are you running your classroom as a BLM support group as in your analogy? If your history shows you are supportive and inclusive to everyone and we’re just trying to provoke thought, I still think you’d be fine.

Now if you’re a math teacher that gets on the topic of BLM three times per week (obviously outside of your prescribed curriculum), the answer might be different.

I still think it’s a good analogy though.