We all have our sore spots, and one can't always stop feeling something simply by deciding one shouldn't. So that expectation might be too high. One can, though, be aware of them and stop oneself from responding reflexively when they come up. (Or, more easily, edit the defensiveness out of one's comments after writing them.)
The quantity and range of posts to HN—plus the fact that there's one big site/community and not a bunch of little siloed ones—guarantee that whatever buttons you have will eventually get pushed here, just like any exposed spot will eventually get wet in a rainstorm. This isn't personal; it's a statistical process. But we're not hard-wired to experience statistical processes, so unless one is careful, it feels like one is dealing with a person—usually an annoying adversary with demonic powers to drive one crazy. I think this is why people often post comments personifying "HN". We each have a different imaginary arch-enemy in our heads.
I mention this in the hope that it might be helpful to anyone else who recognizes the pattern. In our case, exposure to it is an occupational hazard, so we've had little choice but to learn about it.