And in the "filmwad" article, it mentions shooting the assassins. In truth, their throats were slit which makes it even more unbelievable that it was Fredo. I'll agree that the killers of the assassins issue is not addressed and maybe should have been.
Michael says to Tom that same night: I give you complete power, Tom, over
Fredo and his men, Rocco, Neri, everyone.
So it doesn't have had to be Fredo himself but rather some of his guys who killed those assassins. Obviously these men did not need to be implicated in the film as it centered on Fredo. Fredo's men are insignificant for the viewer.
