User blog comment:Ygrain/Leviathan: Do you know what you are doing, Bioware?/@comment-5008642-20120907184306/@comment-2228120-20120907205535

Copying from my comment down below: "Finding out who or what controls your invincible enemies is pretty vital information; the fact that the game fails to reflect that is, well, sad. And, it doesn’t really matter what Shepard would or wouldn’t be able to do with the information, the failure is that the issue is not addressed in any way at all, not letting him even enquire about it"

And how could they know where the Catalyst is? Well, as I stated in the blog itself, they are knowledgeable enough to be aware of the construction of a weapon that was never finished; they even know that it was built more than once. And, even if they didn't have an idea, it really wouldn't hurt to ask :P