How can one believe that ice obstruction can lead to such a result ?!
First we have 4 LP pumps in the tanks, meaning a quadruple simultaneous obstruction, reducing the fuel flow to a SIMILAR value on both sides (resulting in this just above flight idle thrust). This looks unrealistic to me.
In case of ice obstructions, the fuel restrictions wouldn't have been exactly similar, and thrust values would have been different on each engine.