I think the key thing in your example is that both parties resorted to ad hominem attacks almost immediately. I would say both of them were trolling. They should have discussed the content, not eachother's reasons for their edits.
As long as you stick to discussing content, not people, you should be safe from accusations of trolling. I suppose repeated frivolous complaints about content could be considered trolling, but in most cases trolls complain about people, not content.