China has a $2,000,000,0000 a year industry making fakes. Lest you think this is just the odd Rolex or Gucci bag for a laugh the China PLC inventory includes millions of fake car and truck parts not caring one whit how many people are killed thereby. More sinister is the the fake pharmaceuticals which often are not simply benign white chalk pills but random chemicals found out back in the garage, once again not caring one whit who or how many die.
In the case at hand the only other remotely possible explanations are a multiple bird strike of epic proportions or fuel exhaustion. Give credence to the former if you like, to the latter, well, you will need a lower opinion of BA aircrew than is common.
I dislike these "False Choice" arguments. We don't know the cause at this stage.
I can think of all sorts of other reasons the engines might not have responded, for example, differential expansion of fuel control componentry which was apparently at the root of the B737 rudder problem.
Could we please wait and see?