[Ibrîniðilpathânezel]

I might be inclined to say that Húrin was an unwitting informant that provided useful but not specific information, rather like revealing to someone that Topeka is in the state of Kansas. Maeglin was a traitor, and knew precisely what he was doing; he provided exact directions, showing that the direct route into Topeka was I-70. The residents who wanted to keep their location secret would not thank either of them, but if Turgon believed that even the general location of Gondolin would remain hidden forever, then he was allowing hubris to overcome common sense. Which of course he did, ignoring Ulmo's warning. In the bigger picture, one could view the curse upon Húrin as being a part of the already extant curse upon the Noldor, since it did play a part in the eventual manifestation of that curse upon Turgon and his realm.

Hmm, I think the heat may be cooking my brain....