This incident appears to confirm the wisdom of a checklist action on evacuation. 99 time out of 100 we do the evac from a screaming high-speed stop in the sim every 6 months, when, as said, the drill is to lower flaps/open DV etc etc on the slow-down.
A cunning and wise TRE will inject just this sort of scenario into a recurrent - it really is different and VERY easy to rush into an evac with flaps up or even engines running.