Should I Report Him To HR?

So I was browsing people I know on Facebook and I came across someone I vaguely know from work. He works in a different department from me but once in a while I end up having a bit of small talk with him in the cafeteria on break. He seems harmless enough....

So anyway, I had a look at his Facebook wall and noticed that he shared and then got into a politically charged discussion about Trayvon Martin a few years ago. During this back and forth conversation between him and a couple of other people he used a racial slur and basically said that Trayvon deserved to get shot.

My initial thought was to simply report his comment to Facebook (which is what I have done), but now I am thinking that I should really do the right thing and take it a step further by reporting him to HR at work. Part of me thinks he deserves to be reprimanded but the other part of me is concerned in case he somehow finds out that it was me who reported him....

What should I do?