See, I would actually argue that Gulool Ja Ja would have been completely unable to save Mamook, because their more material problems (i.e. weird soil leading to difficulty with crops) are held prisoner behind their ideal of 'blessed siblings are the solution to all our problems' that was, itself, causing even more problems. So even if Gulool Ja Ja could solve their more material problems (which I doubt he could, especially with the Head of Reason dead), all that actually does is further entrench them in their self-destructive desire to destroy their own society in favor of trying for more blessed siblings.
And Sphene is a complicated character to the point where she's very difficult to make a claim of morality on, but that complexity itself makes as linear a claim as 'Sphene was evil from the get-go' wrong. I think that in this context a straight claim of morality is worthless, but that Sphene was ultimately doing what she felt was necessary for her people, despite knowing that it would cause bloodshed for others--in fact, she was very clearly not comfortable with that, even if she felt she had to.
