You really, really, need to see an employment law attorney. You don’t understand the law here, and evidently neither does anyone else in your management and that lack of knowledge is going to hurt you and your company. You seem to think that the employee has to prove that there were “racial tensions” or that the employee needs some kind evidence of overt racism, e.g. a memo saying “Fire John because he’s Black.” Of course those things would help make a great case against the company, they are not required for the employee to win. All the employee has to do is show that he was treated differently than similarly situated employees of another race to set up a prima facie case for illegal race discrimination. You’ve already said that occurred, and the employee likely won’t have much trouble getting proof of that in discovery. The company then has to show that its actions were motivated by something other than race. This is why solid documentation by the company, documentation your company seems to lack, is so important. Imagine the employee showing in court that he was treated differently than the white employees and asserting that shows that race was the motivating factor behind the termination. The company comes back and says “we fired him because he just didn’t fit our mold” as its defense. May as well get ready to write a large check to the employee when the trial is done. If you don’t think a jury wouldn’t read between the lines and figure out that what the company meant was “we fired him because he didn't fit our mold because we are white and he is black” then you’re seriously burying your head in the sand.
Let me see if I can make this clear for you. The employee doesn't have to show the company managers were racists to win. The employee doesn’t have to show that the manager’s express reason for firing him was race. Those help, but aren’t necessary. All the employee has to do is show that the company treated him differently because of race. And if you treat the one black guy differently than all the white guys and don’t have a good explanation other than race to explain the different treatment, a jury may conclude that race was the reason. In short, a lame or clearly made up reason won’t get the company in the clear.