Sorry to be a little bit rude here, but this is such bunch of crap. The person reporting this is not "putting someone's livelihood in jeopardy," the person who did something report-worthy is. There are two situations:
1. The offender really did say things offensive enough that, if reported, HR might fire him. In this case, it's his own damn fault if he gets fired, not the fault of the person who reports him.
2. Maybe after looking at the context, HR decides that the guy wasn't offensive enough to fire. Maybe he's warned, or it's otherwise worked out amicably and everyone's happy. Again, whatever happens is not the reporter's fault.
It's not the reporter's responsibility to hide things from HR. If the offender has a wife and kids and who knows what else, maybe they should not do things that might get them fired.