I think Tom was the most loyal, and I am sure Mike was verbally keeping him down to make sure he didn't dispute any of his decisions because he was a former consilierge (??) to Vito.......I mean, look how much Sonny and Tom argued.....Tom was just as smart in the business as anyone......Mike new that, so maybe he was mean to Tom to try and keep him from interferring with his opinions.
I do think that Tom would have entertained a new move in his life......I mean he went from the #2 man in the family, to just a family lawyer......he probably was pissed off. lol.