I think part of the unwillingness is due to the incorporation of external third party IP they realise they have no real prospect of being able to get a license

I think part of the unwillingness is due to the incorporation of external third party IP they realise they have no real prospect of being able to get a license to open source. In some areas like imaging this always seemed to be particularly problematic - from memory, some of the early "Sony Mobile" Android devices (thinking Xperia Z, Z2 era, etc.) actually used TrustZone DRM to prevent use of certain imaging libraries they had "licensed in", in order to discourage/prevent reverse engineering of them by users that had unlocked the bootloader and thus would likely have root access to facilitate meddling with them. I believe that people eventually removed the TrustZone checks, but the intent was clear. This isn't Qualcomm directly though, but I imagine it shows part of the root of the challenge here.