A useful guide as to whether phrasing and nomenclature is appropriate is to ask yourself if your post shows OOC respect for the organisations or players you're describing.
To specifically address the example of piracy, VETO, for example, is a self-described pirate corp. I quote from the corp description: "Veto Corp has also been linked to tens of thousands of cases of border region piracy..."
Would I describe Veto as a pirate corp in a post on these boards? Yes.
Rote Kapelle, on the other hand, although ICly set negative to my character and her corporation because of their IC definition of 'piracy', RP as I understand it as revolutionaries in the cause of freedom. Whatever my character's IC opinions of their behaviour, I would not call them 'pirates' OOCly.
If I were discussing, say, TS-F, a corporation specifically affiliated to one of the 'pirate factions' i.e. non-Empire factions, I might describe them as a 'pirate faction' corporation, but not as 'pirates', because, again, their RP is not 'we are pirates' but 'we serve Sansha.'
And, to put it in the same terms as the originally moderated post, saying "Pirates include Veto, The Bastards - and at the very end of the spectrum maybe Ghost Festival, although it is debatable if they still do count as pirates" would earn the loving attention of your moderation team, as it is OOCly dismissive of the RP of the players in that corporation and does not respect their right to define and describe their RP for themselves.
I hope that clears things up for you and will assist you ensuring future posts are within the guidelines and standards of the boards.