Abuse of the reporting system within the forums would be using alts to report a post. Being wrong when reporting a post isn’t abuse, and Blizzard would never punish anyone for being wrong if they report a post due to it could discourage players from doing the right thing in helping keep the community clean.
As mentioned by Vrakthris in another thread a while ago.
Now, if you feel someone is violating the Forum Code of Conduct, report the post, and don’t engage. If you have to, you can also place the user on ignore so it hides there post so you don’t have to engage as well in future.
Keep in mind, disagreements are not against the Forum Code of Conduct, and someone posting in your thread is not against the Forum Code of Conduct either.