Fork. Setting up a whole new project infrastructure, getting fellow developers on board with your putsch and everything can be a PITA but all those are natural hurdles, due to how the licensing works the BDFL has no way to stop you.

As such, as a BDFL you rule by the grace of authority of the bootmaker. If you don’t make sense, if you aren’t respected, sooner than later the community is going to leave you behind.