Adam would not have ended conflict stemming from racism. At best, it would have meant racists would be more subtle about how they went about hurting black people. And eveb that is wishful thinking. Black people are already treated like **** because the rest of the world sees us as inhuman. The existence of an actual black superman would only exacerbate this feeling. You'd have white supremacists scrambling to turn themselves into supers on par with Adam, the police force being militarized further, etc. The entire situation was a powder keg that Adam didn't want to make any worse.
As for Icon, like you said, he did work from the shadows whixh was the best he could.