Hi,
Wish you the best of luck with your sale. Haters gonna hate, don't let them discourage you.
But one thing I have to say, and please don't take it the wrong way: The impression I have is that the negative feedback is not so much for cyber-squating claims (which is definitely not what you're doing), but more for the fact that you're using the 10% charity as a sales pitch and not just a good faith anonymous donation. The domain itself is valuable enough you'll be cashing it as soon as I finish this post, you don't need gimmicks imo. I would personally omit the 10% charity (but for honesty sake, I would also probably keep all the money and invest in other stuff).
Good luck