At Carlo and Connie's wedding -
Michael goes on “He's a good lawyer not a Sicilian but I think he's gonna be consiglieriâ€
This is actually a very revealing bit of dialog because it reflects that Michael was not in the Family business at that time--even said (after the bandleader story), "That's my family, Kay, it's not me." "He's a good lawyer" is Michael's opinion of Tom's professional qualities--Michael, the former and about-to-be returning college student at that point. "Not a Sicilian, but I think he's gonna be consigliere" is Michael, the family outsider, reflecting on a decision his father will make that has nothing to do with him.
TB, that's where I disagree with you. Michael's comment to Kay that Tom is not a Sicilian is not Michael's appraisal of his father's impending Consigliere choice; rather, it's evidence of some resentment Michael directs toward Tom. That resentment is further emphasized by Michael's statement to Kay that "he's been with us ever since." That's quite a non-affectionate, non-familial statement about Tom that may very well have its roots in Michael's perception of Tom as an interloper, someone who absorbed much of Sonny's and his father's attention, interaction, and affection.
Another thing: if Michael could distance himself from his father, should we be surprised that Michael could resent Tom. Also, as you pointed out, the flashback scene further demonstrates Michael's resentment of some one who would try to manipulate his future.
