My point is that proprietary code being proprietary also only matters if you don't want to get sued. There is a view that the GPL is more dangerous than propri

My point is that proprietary code being proprietary also only matters if you don't want to get sued. There is a view that the GPL is more dangerous than proprietary code. This is untrue: it is strictly less dangerous. If you are somehow not worried about being sued over proprietary code (which, to be clear, seems like a bad approach to me), you shouldn't be more worried about the GPL. You also have no guarantee of negotiating a license from the owner of proprietary code, and such owner is way more likely to have lawyers than someone who posted a patch to bash 10 years ago and them disappeared from the internet. (Also, for GNU projects, GNU has a policy of requiring copyright assignment to the FSF, mostly because the FSF does have lawyers and are unlikely to be willing to negotiate a private license. For non-GNU software, agreed, but, "This vendor went out of business and we have no idea where the copyright ended up" isn't unheard of either.)