We need a Linux for BMCs. Oxide is working on one, but I'd like to see a contender fielded from the seL4 community, along with some other folks. For example, why doesn't Wind River have one already?
GPL can force manufacturers to cooperate with users. Of course, they can still use closed source binary modules and userland programs ...
The BSD "freedom" is not for the user of the software, it's for corporation to take.
The original BSD release will stay open and free for everyone to utilize.
If it's GPL you can at least interrogate the code release and make an informed decision