I don't know, maybe I misunderstand your posts, but Black Eagles don't seem like a terrorist group to me. They use terror on terrorists, spies, and corrupt officials, etc. They don't blow up a bus load of kids on the way to summer camp, for example.
No, but the definition of a 'terrorist group' to me atl is one that effectively use terror as a weapon, regardless of intent or goal. Make no mistake, while the SDII is meant to be the good guys that protect the Fed from malign entities like the above mentioned spies, traitors, rogue/corrupt leaders and so on and so forth, this does not prevent them from being viewed (with good reason) as an entity to be feared.
If the Black Eagles are in your hood fucking things up, there is usually a good damn reason, but they are still out fucking things up. It's their jobs to be the 'secret police' (not that secret, really, more like notorious) and to, if needed, level the place to the ground and spreading fear in their enemies. This effectively means they can be considered a terror entity to any citizen, regardless if that citizen has reasons to be afraid or not. They do the needed jobs and get them done, regardless of moral stance on such actions by their own government.
And as I've stated before, this makes them a shadowy side of the Fed and one that helps underline the 'we are really gray too' aspect of the Fed - their ideals are good and all, but SOMEONE have to be the hard-asses.
Every nation in EVE has people like this. It's just that the Empire and Federation has more 'known' unknown forces available.