Bookworm, you compare stalled and not stalled, but you have to consider what happens when moving into a stall. The rudder is to prevent making a not-stalled condition of a wing into a stalled condition (first thing they learn you when practicing stalls is to keep the stick/yoke centered at all times, isn't it?)
In a spin ie (both wings stalled), yes, the roll continues. Normal turn (both wings not stalled), the roll is stable.
However, when at high angle of attack, close to a stall, if you move the ailerons, both wings encounter a slightly changing AOA. For a turn to the right, the left wing (downgoing aileron) will get a slight increase in AOA. This can make the wing stall. So while you expect the left wing to go up, it goes into a stall. The right wing has a slightly lower AOA and will not stall.
That's how it was explained to me, I believe you can compare it with a snap roll? Never done one myself, but the demonstration of the snap roll on a A152 was one for the memories (the instructor caught me by surprise and it was almost
-time
)
And forward vs sideslip. Always like they way they named it. With a forward slip the nose of the aircraft is pointed to a side, and with a sideslip it's pointed forward. Both are uncoordinated. A crab is coordinated and flight-technically nothing more than flying straight ahead (no turn). You almost always crab in cruise...
(ps was the article on jets or piston aircraft? it can make a difference)