This is an incredibly stupid take.

1. Why would Baker have accepted half of what thought he could get? There's hundreds of millions of dollars at stake.
2. Just because they're in the same party doesn't mean they don't have diametrically opposed goals. Sununu is responsible to his constituents in NH, a group that does not want to pay income taxes. Baker is responsible to his constituents in MA, a group that does not want to lose substantial tax revenue to fund it's social programs.
3. If Sununu accepted half, that would piss off his own constituents even more. You either believe you are in the right and take it to court, or you don't. He did, and the SCOTUS declined to take up the case.