I for one I'm not too quick to crucify, not going to get into a deep discussion of security sensitive procedures but it is not uncommon to be holding that switch for a while because your partner turn around to answer a question from the CA, it only takes a few seconds of being distracted not to notice that the ailerons are deflecting in the opposite direction to compensate until the AP gives up and then all of a sudden he found himself in an almost hard over rudder situation, single pilot, without enough tolerance in a specific orifice to put a needle trough and this didn't turn into a smoking hole on the ground, we all know that some rudder events weren't that lucky and this was with two pilots working the problem. It is not that I am not critical of the event, I'm just looking at it from the perspective that this paid hobby of ours teaches very heavy handed lessons.
Next time you are doing recurrent, most of the times one finishes early right? tell the checker running the sim to climb you to 350 and then while you are turned looking at the back of the sim, do the same thing, operate the rudder trim until the A/P disconnects, I know it is not a true test because you are expecting it and he wasn't, but it will give you an interesting perspective as to how easy this could have ended in tragedy.