10.11.6 Nvidia Drivers broken again on 24th September by Apple Security Update Public Beta 2016-002.
I have applied the Apple update as of today and am not getting any warnings about 15f03, unlike your example above.
However I am having kernel panics in NVIDIA driver, that started spontaneously (before any driver changes) yesterday. This is what drove me to patch El Cap and try 15f03. It did not fix the problem
Last night I applied the old beta driver package and now my GTX 950 is working. 12 hours of heavy Lightroom use, no issues.
WebDriver-346.03.15b01.pkg
So I'm now on the last update OS X El Capitan 10.11.6 (15G1004), and still none of the drivers installed work
I've never gotten as far as you even seeing NVIDIA driver options in the Driver Manager.My OSX 10.11.6 build number is the later 15G1104, suspect that is due to BETA program.