I think you’re hung up on what “up” means. In an airplane there are always two "up"s. The one from the center of the earth towards the sky and the one from the bottom of the wheels up towards the top of the vertical fin.
In straight and level flight the two ups are aligned. They are not the same, but they are aligned. In inverted flight the airplane-centric up and the earth-centric up are directly opposed.
In a conventional 30 degree banked turn, the ups are misaligned by 30 degrees. With the result that some of the airplane’s lift forces pull it around the turn. And, that means those lift forces aren’t available to counteract gravity, so to maintain altitude while turning somehow you need to add lift in the earth-centric up direction. Which we do with some back pressure and added power. More total lift in the airplane-up direction is created, and it is divided between pulling the airplane around the turn and holding the airplane up at a constant altitude against ever present gravity.
So far so familiar, if maybe explained in terms more appropriate to an aerobatic pilot than a cross-country cruiser pilot.
Now switching to the stuck elevator scenario …
If you had an elevator hard over, that will force the airplane’s nose upwards in airplane-centric coordinates. And that resulting turning in the airplane’s vertical plane of motion will put positive G-force on the overall airplane & wings, and negative G forces on the tail.
Rolling 90 degrees (just for concreteness let’s say to the left, so left wing down, right wing up) does nothing to change those things. The airplane is still being uncontrollably G’ed. And will keep turning in the airplane-centric vertical plane.
What does change, as you say, is that now the elevator / G induced turn will be in the horizontal plane when viewed in Earth-centric coordinates. So you’ll be making an extremely tight left turn from the earth POV, perhaps with enough G on the wings to break them right off the airplane.
Meanwhile, while you’re in 90 degree knife-edge flight, there’s no force holding you up against gravity. So you’ll be plummeting earthward & viewed in 3D your tight left turn is actually a tight spiral downwards. With a powerful enough rudder you can yaw the nose in the airplane right = earth up direction. And get some lift in the earth up direction from the left side of the fuselage being exposed to the relative wind directing it downwards. Fuselages are very inefficient wings, and most airplanes cannot maintain altitude and airspeed in knife-edge flight. The ones that can are high-powered aerobatic planes with huge engines who can more or less hang on the prop, held up as much by the partly downward-directed prop thrust as by lift from the fuselage. And meanwhile there’s enough prop thrust available along the line of flight to keep the airspeed up despite the drag from the yawed fuselage.
Bottom line: Starting from straight and level flight, a stuck or hard over up elevator will cause the nose to be uncontrollably raised skyward in an attempted loop which quickly will run you out of airspeed and lead to a stall or spin.
Rolling 90 degrees stops the “skyward” part. But that’s all. The stuck elevator is still uncontrollably pulling the airplane nose up in airplane-centric coordinates. Which is now parallel to the horizon, but still uncontrolled / uncontrollable.