firmware and avoiding non-free software

When talking about distributors choosing not to distribute proprietary firmware blobs as part of the Linux binary image, the suing that they want to avoid is where they the distributors (and their mirror providers) are sued by one of the copyright holders of some GPLv2-licensed piece of code in Linux.

As for why a Linux copyright owner would sue a distributor, maybe some separate disagreement arises and the copyright owner uses the threat of suing as a bargaining chip, or maybe the copyright owner is a company (see SCO).

As for the copyright owners of the firmware itself, they have grounds to sue if the firmware blob weren't licensed for distribution at all, or if the Linux binary image that contains that firmware blob is considered a derivative work of the firmware blob (which seems less likely than the above case), and if the firmware's license hasn't granted permission to distribute derivative works of the firmware. I haven't heard of distributors being concerned about this case.

Going back to the question of to what extent “tearing firmware out of the kernel [Linux]” is evidence of a desire to “avoid anything non-free”, I believe that in some cases the distributor still distributes the firmware blob, but as a separate file loaded into the device from userspace. (Moving the firmware blob out of the Linux binary image in this way makes it clearer that this is an instance of “mere aggregation of another work [viz. the firmware] not based on [Linux] with [Linux] ... on a volume of a storage or distribution medium”, and much harder for the would-be plaintiff to argue that these separate files form a single work that is a derivative work of content of either file.) If a distributor is still distributing the firmware, then clearly they are not trying to “avoid anything non-free”, but are merely trying to avoid copyright lawsuits.