This is why developers should AGPLv3 their personal projects from day one. Then others can't fork it under another license.
Even if they choose AGPLv3, the creator still maintains full freedom since they own the copyrights. They can make a commercial version if they want to. They can even relicense it under favorable terms to companies for a licensing fee. Everyone else must abide by the copyleft rules.
If they don't like it, let them pay hundreds of thousands of dollars a year for their own developers to make their own in house proprietary version.