If the relevant authorities did in fact, designate the organization as terrorist, then or now, that designation might well be significant enough to be in the lede. No agency did that at the time because the conception of terrorism was different in their day than now, and none is likely to do so now because there is no agency charged with making retrospective historical judgments. The history editor from the FBI's website communications department is not the one to make such an announcement. This article does face this stuff regularly, so the editors who have watched it for a while do not have a very high patience level for shenanigans. That's not ownership, that's taking the encyclopedia seriously instead of letting political sentiment color things. -