From my recollection, Vito does not state that a capo will betray Michael. But we do have Michael recognizing, of the two capos, Tessio's superior intelligence and, from all appearances, the betrayal is a smart move. Tom stating that it would be Clemenza is probably just an exercise of directorial license to set up Michael's statement about Tessio.
"Generosity. That was my first mistake." "Experience must be our only guide; reason may mislead us." "Instagram is Twitter for people who can't read."
