Discrimination is bad. It’s bad for the person being discriminated against; it’s bad for their team. Reporting discrimination is not an easy thing, whether you’re the victim or an observer, but it is the right thing.
Forget the fact that obvious racial/religious/nationality discrimination opens the company up to a lawsuit. Forget the fact that the victim could report it himself “if it bothered him”.. It bothered you. You noticed it. The rest of your team noticed it. It made you mad.
People being victimized can’t always see clearly. Do the right thing, even if it is not the easy thing.