The simplest way to vet that explanation was to simply click on my profile and see that I've been here for years with a karma count that certainly doesn't trip any shill account alarms.
Astroturfing is only one of many possible motives for a comment being left. We should not be so quick to jump on that as an explanation for anything which doesn't agree with our notions.
Please refer to https://news.ycombinator.com/item?id=6320222 for the reasons I found kyro's comment very PR-like. I expect, and will remain expecting, HN comments to be based on reality.