I think your being a little overly critical on what Apple said. Fredo wasn’t very smart; this point is shown many times in Godfather Part 1 & 2. Can you name 1 thing Fredo actually did which would portray him as being smart or smarter than we give him credit for? I for the life of me cant, I can though think of actions which were stupid on his part.

- Fumbling his gun when Vito got shot - Okay anyone can get nervous but it didn’t look good on his part.

- Siding with Moe Green in an argument with Michael, the first sign of things to come

- At Anthony’s party, he could not control his wife, shows he was quite a weak man.

- Helping Roth & not realizing the repercussions of those actions

- At first telling Michael he didn’t know Johnny Ola, then later at the Superman show, letting his tongue be a little too loose gave away that lie.

- Not leaving with Michael after the New Year's Eve Party that maybe construed as a smart move because he might have thought Michael might kill him but we knew that Michael never planned to kill him until after his Mother died. So not leaving with Michael made the situation worse

- Believing that Michael had actually forgiven him, we all wanted to think "Yes, Michael can let this pass" but this was the 2nd time Fredo went against the family, if Fredo was as sharp as his brothers (maybe not Sonny) then he would have realized.

Sure there are others too but I’m sure from that compiled list we can agree Fredo was pretty dumb and not ‘SMArt’ as he described himself.