The real meaning behind patent infringement concerns is that the source code contains clues to the "secret sauce" that the binaries don't make readily accessible. So publishing the source is publishing the restricted IP. Whereas their license to use the IP allows publishing of the binaries.
There's no way to avoid giving away clues to "secret sauce" when releasing a driver, and keeping the source code closed doesn't change that. I don't see how the degree of accessibility is relevant.
The fact is that clues to IP can't be removed when compiling the source to binary form, because implementation details can't be hidden. So the status quo is that they are already public. Granted, it takes more skill and patience to analyze the clues in this form, but any competent hacker can do it. And the absence of names and comments in the binary makes the job harder, but doesn't actually remove the significant clues.
And while it's true that these drivers might be using licensed code, which restricts publication of its source code, this seems like a poor excuse for keeping all the code proprietary. The existence of licensed code doesn't block releasing the rest of the code. And I'm willing to bet there is an army of volunteers out there that is more than happy to write a clean room replacement for the licensed parts, if the vendor can't do it, given the opportunity.
