What are the ROE respecting when the suspect had refused police orders to stop, had jumped a subway turnstile and exhibits behaviour that gives every reason to suspect that he is about to set off a bomb in a crowded subway car?
I suspect that in similar circumstances the NYPD would have shot him in the head, and probably before he got to the car.
Consider the number of shots fired by NY coppers at a suspect who was reaching for his wallet in a dark stairwell and compare the downside risk in that situation to what was confronting the London coppers, especially the downside risk to civilian bystanders.
A dog smells his own arse first.
The retrospectroscope is a marvellous instrument. It enables much clearer thinking about what you would have done had you had all that after-the-fact knowledge and several days instead of mere seconds to comtemplate the appropriate response.
That would be a great tag line if it wasn't so long.