you what now? Sending him to the wall is not putting differences. Just because Joffrey is a (dumb) cunt of supreme proportions (only Ramsey would have done this), it doesn't show some mercy or work out for her.
What exactly can Cersei do to Tyrion? She has zero power, and her son is too much of a punk bitch by that time to do anything to Tyrion either.
The third point literally ends with all of them being blown to pieces, what did she do to work with the Sparrows? She aligned with the Sparrow because she underestimated him so he could hurt the Tyrells.
Saying that, I can see her forming an alliance while waiting to stab them in the back (in this episode).