Hello Rob,
Unfortunately, the screenshots seem too low resolution to be legible from my end.
Disabling in Device Manager doesn't switch off the graphics in the kernel at run-time.
Microsoft told me there was no point in doing so, any setting after boot is too late. It's about when the change is done regarding to the progress in the OS loading rather than when in time. It may change the behaviour for some
applications, not for the
OS itself. DisplayLink is not an application: we render pixels we get from the OS, we don't see applications, windows, menus or other objects.. we get computed pixels.
Have you observed any increase of general graphics performance after rebooting?
Upcoming Windows 10 includes a switch in the Windows Settings looking identical to some nVidia and Intel add-on application features.
They blogged about it. I don't believe it works either on indirectly connected displays though yet. It's in the queue to be checked internally, but I haven't put it as a high priority as I don't see why it could possibly work.
We all need to keep pushing through the Windows 10 Feedback Hub to show it is important to us. Microsoft asked us to because this is how some new features are prioritised.
You are correct that today it doesn't fundamentally matter if the add-on app returns an error or not as it has no effect, but I feel it would be better if that application could start and understand a standard Windows feature introduced in the Windows 10 Anniversary Update. It most likely is a matter of priority rather than unwillingness to address.
Kind regards,
Alban