Speaking in absolutes like this will make you look stupid down the road, when it comes to BB and the Patriots.
The sample size with Jimmy G is too small at this point to know for sure but if he is the guy that we saw tearing up the Dolphins defense in week 2 last year.... you can't win the Super Bowl with that guy? Give me a break. With all of the offensive talent that he would be surrounded by next year, along with what has the potential to be a top 5-10 defense, he definitely, 100% would not be able to pull off a SB victory next year? Give me a break. He's not a rookie anymore. The playbook is second nature to him at this point and BB himself already stated last year that they do not have to change the game plan when he is in at quarterback.
In my opinion, one of the main reasons that the patriots are unlikely to trade Jimmy G is that they believe that he COULD win a Super Bowl for them, if, God forbid, Brady ever goes down. You could not say that for Brissett or any other potential new acquisition (trade/draft/free agent). They have amassed an impressive amount of talent on both sides of the ball and are the overwhelming favorites to repeat next year as Super Bowl champions. Having the chance for a sixth ring down in flames with an injury to your 40-year-old superstar quarterback is bad planning. Not having a viable contingency plan is not the patriot way. Jimmy G is their a contingency plan.
In summary, based upon Jimmy G's limited game film last year along the patriots actions and statements with regard to him, I believe that BB would say that you are misinformed and, frankly, ill-equipped to make such a definitive statement.
Another way of saying this is:
Tough call, but I'll go with BB on this one.