I am totally not a laywer, but as somebody who's been participating in and/or observing the F/OSS world for a couple of decades now, my belief is that it's a co

I am totally not a laywer, but as somebody who's been participating in and/or observing the F/OSS world for a couple of decades now, my belief is that it's a common practice to do what you're describing. That is, "project has code under F/OSS license, project goes private/proprietary, so somebody forks the last version that was released under the F/OSS license." That pattern has played out over and over again, and I don't recall ever hearing of any legal consequences for doing so. Now, their might have been some legal saber-rattling or threats and insinuations hurled around. But not aware of a case where anybody actually lost a legal case or was punished for doing that. But again... IANAL, this is not legal advice. If you're seriously concerned, the best bet is to contact a licensed attorney who practices in your area and pay them to give you advice.