I am no medical professional or anyone qualified to diagnose anyone, but just on my own personal interactions with manipulative people.. I think sometimes those closest to a person don't see it because they aren't the target of the abusive person. Often people can be one way with their target and a very different person with everyone else. Doing all things for everyone else, bending over backwards to help others, put on a smile, be the "nice guy" and the "family man" and it really can do a number on the people that don't see the bad side. Maybe they get tiny hints of it, but the good in their mind about that person don't line up with what they are being accused of. Add in the whole world seeming to be against that person you only see the good in, I think it can make people dig in even harder to support the person. Maybe deep down they have the "what if " thoughts, but outwardly they are going to be seen as strong for the accused.
I also wonder if his lawyers have sat down with many of these supporters (meaning his close friends and family) to talk about how they should be seen, what they should or shouldn't say online or to media/news).