Remember that, just after Michael told Tom he wasn't a wartime consigliere, he added, "Besides, who's a better consigliere than my father?" Then his father died and he needed Tom as his consigliere.
The full line is "besides,
if I ever need help, who's a better
consigliere than my father?" (emphasis added)
I don't think Michael believed he would ever need help, so he didn't feel he needed a
consigliere (or ever had one).
