I agree Babe. Having a "relative" as Consigliere compromises the way the others in the family view you especially if they are "part of the family." I'm not sure that Sonny really perceived Tom as someone who's advice he should take seriously. On the other hand, Tom may have been somewhat reluctant to press his points and strategy with Sonny or even Vito (witness the Sollozzo fiasco).

Sonny was aggressive. That was his value. Mafia killers are a dime a dozen. Its survivors are the ones with brains or the ones that subvert their emotions to good sense.

"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."