I just find it impossible to believe that anything could go that seriously wrong in AFCS yaw that would be more perilous to keep flying compared with the peril inherent in putting it into the water. But I wasn't there. Hopefully I'll be surprised.
Think of it like this, the crew are flying along when there is some sort of AP/Stability issue. The flight controls all of a sudden are heavier/stiffer, the first thought which springs to mind is that of 5N-BGD which suffered flight control issues before it ditched with the loss of 6 lives. Panic sets in and their mind has already decided (incorrectly) that they may have the same problem and decide to ditch before losing control. The actual issue is not fully identified/resolved.
I think its called getting into a 'mind set.'