But thrust is fuel!
NO. As you quite rightly have stated previously Thrust is a Force.
A propeller will consume Power to produce this Thrust, but this
Power comes from that produced by the engine.
Fuel use depends on Engine Power but, due to inefficiencies, this will not
be the same as the Power available to the propeller.
How can more THRUST mean less POWER and therefore less fuel?
Unsure if this is the complete and correct answer but:
Propeller efficiency (how much engine Power it can use to turn in to Thrust)
varies with speed - so it is possible for a Propeller to produce more Thrust for
less Engine Power and hence less fuel consumption.