I wish I had time to dive into this. I think that when you take a step back, way back and look at when the N9 bug started. (One of the first things I would try to find out) What ever it is has now spanned 3 android versions. Even when you look at googles git, development for the N9 dripped like a cliff when Nexus went away from the whole Denver/tegra experiment. Its stuck @ v.1.0 . That also means that the bionic people might not be tracking it. (You do strait compile on kernel source or @ top of device repos??? Hmmmm) That would be an interesting test. I always did think that compiling in a device tree pulled the kernel from being solely Linux over to android a bit more. If you look at the buffer, there is a sack more going on @ make bootimage then strait make @ kernel source.
Or maybe its the long game. See, its happening with everybody. What about repatching the kernel with every sequential update patch from conception on. I just don't know about mass patching and patch bundles.
Another thing is I haven't tried taking a full google update pack from the image site and first flashing it and if it fixed stuff to diff the whole freaking thing. I think it would become clear quickly at that point that it isn't even in the kernel, honestly.
Back on skyrocket, I would rebase my oc kernel every year, maybe add something when it came up like quick charge but that was it. There wasn't enough to do in just the kernel so I posted some ROMs that had my kernel.
Baaaaahhhh! lol
Maybe over Christmas I will try FI with a factory image