If you look at the request made, then it seems to check the category of the site, for whatever reason. I don't know that extensions, so I don't know if this is a legit use, sloppy use or harmful. I'm also not saying they found nothing at all. But looking through what they found, they seem to have not even thought much about whether those cases are legit and in the excepted and necessary realm of actions the add-on is supposed to do, or if it's really harmful behaviour. I also don't see anything about how often the request was made. Was it on every url-change, or just once/occasionally?

This whole article is a bit too superficial for me.