I have finished making a patch to enable/disable swipe to unlock on any device.
The hardest part was figuring out what actually controls whether the swipe to unlock is displayed (it's added/modified in many places). I eventually found it in a unnamed subroutine which instantiates the AbstractPowerView (which controls the widget for swipe to unlock). I then changed the device check and branch to allow me to choose whether it is enabled or not manually.