D,

But this wasn't a normal landing.
The 777 was reportedly circa 500 ft
when the pilot noticed that the engine wasn't responding to greater
power.

Reported by whom? How on earth would you know? Have you thought to ask
yourself why professional accident investigations tend to take months,
even years? We know exactly nothing about what you claim to be fact.
The AIB will issue an inital report in 48 hours. That will be our first
clue. An "airport worker talked to the pilot..."? Bah, humbug!

My Q is that once it was known that power was off,

WE DO NOT KNOW THAT!

shouldn't
the pilot have pushed the nose down a bit to increase the airspeed to
be able to land as further down as possible since a nose-up attitude
with idling or shut engines can only sink the aircraft faster?

Are you a pilot? The proper reaction to a power loss (which we didn't
know happened) is depending on so many other factors that we as
outsiders can't say. That's why there are professional accident
investigators working on this.

--
Thomas Borchert (EDDH)