After Vito was shot, Fredo is not shown again until Vito comes home from the hospital (unless I missed him). Was he totally mortified that he fell apart while his father lie bleeding on the street? I'm surprised anyone in the family wanted anything to do with him after that, which is maybe why they sent him Vegas.
Which begs the question, that since Fredo was known for not being too bright, why would they send him to Vegas to set things up for the families big move? As they found out, he very quickly "took sides against the family".
