I'll generally post here any time I add something to the Wiki.
What's happening in the profiles used here is:
myTRUSTEDWIFI profile - if you're connected to one of the networks configured in that profile (a "trusted" network), the variable %myTRUSTEDWIFI is set to true. If you disconnect, the exit task waits 1 minute, and sets %myTRUSTEDWIFI to false, but only if the myTRUSTEDWIFI profile is not active. The net effect is that if you're connected to a "trusted" network, or have were connected less than 1 minute ago, the variable %myTRUSTEDWIFI is true, otherwise it's false.
myDISPLAY profiles - each time one of the Display events is triggered in Tasker (these are Display On, Display Off, and Display Locked), the variable %myDISPLAY is set to a value corresponding to the most recent Display event. This allows us to, at any time, know the current state of the display (something you can't do with just an event).
myUIMODE profiles - if the device is powered and in an upright orientation and %myDISPLAY is unlocked, %myUIMODE is set to car. If the device is powered and on its left side and %myDISPLAY is unlocked, %myUIMODE is set to desk. If the device is not powered and neither of the previous two profiles are active, then %myUIMODE is set to normal. The net effect is that once the device is powered and upright, or powered and on its left side, %myUIMODE will be set appropriately, and will remain set that way until power is removed.
Trusted profile - whenever %myTRUSTEDWIFI is true AND %myDISPLAY is unlocked, the PIN lock is disabled.
Car Mode profile - whenever %myUIMODE has a value of car and %myDISPLAY is unlocked, the PIN lock is disabled.
Untrusted profile - whenever %myTRUSTEDWIFI is false and %myUIMODE is not car, the PIN lock is enabled.
The net effect of these three profiles is that if the display is unlocked and, connected to a "trusted" network OR in car mode, the PIN will be be disabled.
I've been trying to find a good way to explain why the device must be unlocked before the PIN is disabled, and right now I'm equating it to "approving" the disabling of the PIN. This more important in the car, since you don't want anyone finding your lost (and locked) device being able to unlock it simply by plugging it in and holding it upright.