With the blade angle fixed at 3 deg, even with the engine torque at zero, it wouldn't help them. Think of it as a very small gyrocopter's free spinning rotor descending in autorotation straight down (they can do that); it's making enough lift to slow the descent quite a bit (some autogyros with special landing gear can do vertical landings). An engine with a prop fixed at 3 deg blade angle that is free to spin will spin madly in autorotation like a gyro going straight down, generating massive lift aft (instead of up, as in the case of the gyrocopter).
Having the blades stuck at that position, the only hope would be to have the blades forced to stop spinning and stay stationary, making the blades just act as speed brakes with an AOA, in our case, of 87 deg. But they have to be prevented from turning. As soon as they start turning they will start making negative lift.
So, theoretically, if the airplane had a propeller brake (which some airplanes do; it allows the engine to be run at idle with the prop stationary) and it was engaged while the engine was shut down or at idle, the drag of a propeller that is braked and prevented from spinning is a fraction of an autorotating propeller (basically, the difference between a gyrocopter descending straight down with its rotor spinning and making lift, and a gyro with its rotor held stationary with the blades producing drag only and slowing the descent only slightly below falling object velocity).
A turboprop like that with blades flat and locked against rotating would probably be able to maintain control, and might even be able to maintain level flight (but probably not climb), as long as the blades are unable to start spinning and making negative lift. So in the end, I'd say the only way to save that situation would have required two things: a prop that can be braked, and time to figure things out and engage the brake.