User blog comment:Legionwrex/Leviathan Review./@comment-1388547-20120829204948

It makes sense that Shep doesn't question Leviathan about the Catalyst as such -- the Commander can ask about the Crucible generically, about which Leviathan doesn't know much, and until Cronos Station none of the good guys even know anything about the Catalyst except that it's some mysterious thing necessary for the Crucible to function. And Leviathan has a fair amount to say about the AI its ancestors created -- which turns out to be the Catalyst, though neither Shepard nor Leviathan know this at that point in the story.

Also, I can understand not getting the Leviathans themselves as war assets (though I'd have enjoyed the chance to see them in the victory fleet) -- they're willing to work behind the scenes now that Shepard has suggested they might have a chance at victory (and now that the Reapers know where they are!) but they've been hiding for at least 37 million years. They're not about to risk their big, tentacled hides on the chance that some upstart species can finally stop the ancient scourge of the galaxy. In fact, I suspect they probably can't spare the time to be personally present for a very good reason -- if they have any sense, they'll be evacuating their site on Despoina to escape further Reaper attacks and gain some measure of safety in case Shepard fails.