[Ibrîniðilpathânezel]

One also has to consider the source of Morgoth's claim that he already had sufficient information. Not Húrin, but rather Morgoth himself. He's the ultimate liar, being the original. He may well be playing Maeglin with that statement, since if Maeglin goes away believing what Morgoth says, he could be less careful, thinking that there is no need to hide what Morgoth already knows, and thereby revealing what Morgoth wanted to know, without any possibility of duplicity on Maeglin's part. Double dealing would not be beyond him, and I don't think any version of the text does not allow for this, even if it fails to make a point of it.