I always assumed that Fredo's betrayal was common knowledge amongst the Family & the likes of Neri, but Michael wanted to deal with it by himself as much as he could, due to the extreme nature of treachery by an actual family member. Obviously any soldier or capo couldn't kill Fredo Corleone without approval, even if they did happen to find him.
Connie could have known all & still been willing to forgive Fredo, Tom would have been waiting for his Don's orders.
The fact that the Don of the Family wanted to take such a careful & hands-on approach in dealing with this particular traitor emphasised:
- just how serious Fredo's betrayal was;
- how deeply Michael was hurt by it.
I don't think there's much else in the detail.
I kind of saw it a different way. First of all i dont think Fredo "betrayal" was that horrible. everybody with half a brain knows fredo was good hearted and din't want his family members hurt. sure he was stupid and jealous but he wasn't evil enough to kill a member of his family. Hell even Al neri who was one of the most emotionless hitmen in the Godfather kind of had a soft spot for fredo since you can tell he wasn't thrilled about having to kill him
I tend to agree. While he could be truculent when pressed, I don't think Fredo had larceny or worse in his heart. Michael's decision to murder Fredo was based on his outrage over Fredo's outburst. Michael considered that outburst a function of Fredo's unmitigated stupidity and that stupidity is what really governed Michael's decision.
Also, I agree about Neri. In a perfect world, Neri would have given Fredo a pass.
