Fabrice Bellard is the author of qemu and ffmpeg (among other things), so it is likely he is aware of the benefits of open source and it is a conscious decision

Fabrice Bellard is the author of qemu and ffmpeg (among other things), so it is likely he is aware of the benefits of open source and it is a conscious decision (maybe there is interest from someone with relatively deep pockets, or maybe he considers it too hacky?) Don't want to speak for him here though. I do wonder how qemu compiled via emscripten would compare though...