If what you say is true (and I'm afraid I haven't been able to follow the discussion at all closely) then it would seem to make sense to only allow selected applications to block suspend, with only the device distributer and the device owner allowed to make that selection.
What I don't quite see is why device drivers want to impose suspend blocks. Does anyone know an example of a device driver that needs to do this? I would have thought that the decision of whether to suspend would be entirely up to user-space. Obviously a device can say "just a moment, I need to tidy up a bit first", but otherwise it should just do what it is told.