I was just thinking the same at first...."he was very convincing and manipulative" seems to be judging his charactor, which the judge said was not to be considered when thinking of the financial crimes. I think there are two ways to consider those words that juror said. Using that information to consider AM a bad man with a terribly lacking character...a no-no inference...OR...Using that information as just straight up fact that AM had a talent to successfully deceive and manipulate. When that "talent" collapsed it helped to change AM's mindset about what his actions were now going to be going forward.
That to me is a perfect interpretation of using that information of deception and manipulation collapse to describe AM's frame of mind and actions...his motive being formed. AJMO