That's an ironic response, some (not I) might say you're being a little insensitive to those who find that word unacceptable to use in any circumstance, though unreasonable it might seem to you, I mean, jeeze, you were only making an analogy was all!

I read your comment and understand that you're not saying the two terms are equal, rather, you're trying to demonstrate that it is not unusual for someone outside of the persecuted group to be offended by words intended to offend members of the persecuted group. Yet, were I the type to take offense, I might find it quite offensive that you used what is widely considered the most offensive word in the English language to make a hyperbolic and inapt analogy.

The word 'nigger' is a pejorative racial slur intended to wound when it is used, whereas the word 'bro' is commonly associated with friendship and brotherhood. And douchebag frat guys.