I can totally see Graendal doing this.
The problem is I think she did die. Not because she wasn't smart enough to outsmart Rand, not because I see any hole in your theory.
Because I think her death was a statement about Rand's character. He went from not wanting to kill any women or innocents to nuking the palace where he was pretty sure Graendal probably was but her innocent pets certainly were. It's a huge leap for him. It's profound. I think if Graendal survived it that would invalidate a lot of what we felt when he did that, makes it less of a game changer.
I want Graendal to be alive. I want her killed off in a dramatic scene where she is her usual brilliant self but just has a small dose of bad luck. I want her to have a moment. I know that convention says if you don't see the body they aren't dead. Unfortunately, I think Graendal is and I think it was ultimately best for the story.