Sure, Facebook could do what they did for RocksDB and use the Apache 2 license (and optionally, the GPLv2). People have been asking/telling Facebook to do just

Sure, Facebook could do what they did for RocksDB and use the Apache 2 license (and optionally, the GPLv2). People have been asking/telling Facebook to do just that for at least a year. The reason Facebook doesn't, I assume—and this is just my personal opinion—is because Facebook wants to do evil shit in the future that the Apache 2 wouldn't allow them to do. Otherwise, I just don't see any value for Facebook in all the negative publicity they've gotten over this idiotic patent grant crap they're trying to pull.