To me, a very plausible scenario: V1, Vr, V2, one engine fails, one pilot tries to restart the wrong one, now you're 400ft AGL with one engine failed and one that was just cutoff, with no altitude to restart it.
If they did, they did not follow procedure.
With an engine failure at, or after, V1, you;
1. Accelerate on the runway to Vr
2. Rotate to an appropriate single-engine attitude (7° - 10° nose-up on my airplane)
3. Retract the gear when a positive rate of climb is confirmed
4. Maintain runway track
5. At 400', engage the appropriate lateral mode and fly the applicable engine-out ground track
6. At acceleration altitude, lower the pitch attitude and retract the flaps on schedule
7. At clean maneuvering speed, set Max Continuous Thrust on the operating engine
8. Accomplish either the "Engine failure or shutdown checklist" or the "Engine fire or engine severe damage or separation" checklist.
The Engine failure or shutdown checklist is the only one that gives an option for restarting and it is on step 14. At that point, it refers you to the Engine Start--Inflight checklist. You will be several minutes into the flight before you reach that point.
Again, I've not flown the 787 but the checklist philosophy will be similar.
Could they have gone against all of their training and done as you suggest? Of course. Could a driver driving down the freeway see an accident up ahead and decide to shift the car into park at 70mph? Also, yes. But, how likely is it?
BTW, the Engine Start--Inflight checklist has 14 steps and no memory items.