That tweet is pretty racist itself. It'd be like if I said about a Native American "with this hug he placed the hex of his ancestors known as the tomahawk chop". Like k. I know your heart is maybe in the right place, but it's a bit fucked up.
As for the whole forgiveness debate. Nobody has to forgive a murderer. Just cause the brother forgave doesn't mean you, your friend, your random uncle, the dead person's cousins or whoever else has to forgive. He did, fine. You can forgive too. You also don't have to. I had a black friend on Facebook express his displeasure with the ruling and I get that. To use the brothers forgiveness as some kind of tool like "yeah you black people should forgive" or "see. If he can forgive then the ruling is fine." are petty takes. Forgive if you want. Don't forgive if you want. Don't use the man's forgiveness for some kind of social currency on race relations in America.
edited for misspelling you're/your