Seems smart to start by contributing a more openly governed path. If Matt starts to fight, sabotage and shut that down it gives the important yeah-we-did-try style cover to the reasonable next step of forking.

By being unreasonably reasonable in this way I would expect they bring the most members of the community with them if a fork has to happen.

They also leave a door open for Matt to leave this effort alone or even welcome it. A potential road to recovering trust over time.