Redis is no longer free software

That's a massive oversimplification. GCC and the Objective C frontend is an older case where the GPL caused the Objective C frontend to be available to everyone. Linux, which became a very large cake, has had decent returns from commercial users; BSD seems to have had relatively little, with the exception of some end-of-life stuff tossed out. Even then, e.g. AdvFS (from BSD-based OSF/1) was released as GPL-2, not BSD, for use with Linux.

Working with giants like AWS and Azure is hard; they have every intent on being compatible with Redis only so long as they have to. They want you locked into Amazon Elasticache or Azure's version. Can a BSD version keep even a tiny slice of cake against that? I'd suspect Redis is going to drift into oblivion as open source users drop it and AWS & friends ignore or duplicate any changes.