The most popular software that was derived from (a number of predecessors and) FreeBSD, Apple’s Darwin, is free software, nobody stops anyone from taking code from there. In fact, quite a few FreeBSD developers are (were?) paid by Apple.
Sony also used FreeBSD in PlayStation 4[2] and to my knowledge their modifications have not been open sourced. I may be wrong though.
[1] https://en.wikipedia.org/wiki/Intel_Management_Engine#Design
[2] https://en.wikipedia.org/wiki/PlayStation_4_system_software
That is true, I should have phrased it more carefully.
> In a way, that makes BSD more free than the GPL.
Yes, BSD is a permissive license and GPL isn't. But the original question was whether GPL leads to more splinters or BSD.
I think that the copyleft nature of GPL leads to fewer "effective" splinters since good modifications can be merged into upstream, and what is left unmerged tends to be less important to the success of the parent project. This has helped Linux gain momentum and unfortunately hasn't much helped the BSDs or Minix. I would like to see the BSDs succeed but I suspect that the permissive license has been one of the impediments to that.