The only part I disagree with is the chance of winning back the starting job. I think Jauron & the coaches have made up their minds that TE is their starter come opening day.
Agree with the other part as answers to Gordio's question. Plus, if he goes somewhere else to be a backup he will be at risk in being let go next year setting himself up to being a journeyman. Big payday next year or not, he most likely thinks that if he is to step in for any length of time, his best chance to showcase his talent is in Buffalo due to, as you said, familiarity with the system but also with the players and their strengths/weaknesses.