I dont know of any implicit significance for the entire scene, but its ironic how Fredo is the only one that realy supports Michael on the choice he made about enlisting.

I've always seen it as Fredo speaking from the grave and getting the final word in before Michael completely isolates himself from everything. frown

Note : GFIII completely ruined this theory as we find Michael having the time of his life before "they pull" him "back in. " He is a much different person than the prematured prince of darkness sitting on the Lake House lawn. So much for consistent story telling. ohwell