Hmm, unsure if I approve of Alice not offing Ardent, or disappointed that she didn't off him.
On the one hand, the one panel makes it seem she had a large hand in the carnage and destruction of the wars before the Blink, and that the experience broke her in a way, which would indicate that by sparing Ardent, she doesn't want to reawaken the monster she once was (though you can see it here and there in the comic). On the other hand, by offing Ardent, it would've shown that she's willing to do what it takes to prevent any harm from coming to the world she's tried to rebuild.
Of course, the second option assumes that Ardent is indeed a pawn/sleeper agent.