BC, I agree completely. However, there are several Board members who are apologists for Michael. Actually, Michael did exile Fredo as you suggest he should have. However, those apologists come up with some bizarre rationalizations about Fredo's continuing threat to Michael. For example, one Board member posted that if Fredo was not murdered by Michael then he could provide Roth with a layout of the Tahoe compound (as if the attack on Michael did not already require that information).

So, you are right. Fratricide places Michael at the apogee of life's degenerates.