I think what saved Zoe was that she immediately accepted responsibility for losing the first 2 pitches...and then generously helped by Edna digging her own grave. It was very hard not to compare her 'MBA' comment with the Sandhurst idiot a season or two ago.
(Not to mention that Edna really ought to have lost the moble app task and gotten fired for it).
Susan, well, last time Zoe was a PM, Susan claimed she could sell huge amount of skincare products and failed to move even a fraction for that and had they lost, would probably have been sacked too.. I would have ignored her as too, had I been in Zoe's shoes.