I’ve seen lots of robberies in my time but have to say I’ve never seen or considered this reactive move! 



That's how the ones work here in AL that I've found...not bad at all, thank goodness.The ones here have a spring loaded seal that won't dispense unless it's pushed tightly into the filler. I regularly fill my own gas cans, 5 gallon cans, by holding that release back so I can see how full the can is. Takes two hands, but works every time.
The problem with these gas cans, they are sealed up enough that they expand until the seam starts splitting and the gas spews out.That's how the ones work here in AL that I've found...not bad at all, thank goodness.
Spent 29 years in N. CA where emissions are tight so that's where they were such a PITA...even the gas cans had devices to close them off to prevent vapor escaping and that doubled the cost.
I have a couple of those *^$&^ things. I wind up spilling more gas than the small amount of fumes that would have escaped. Not to mention that to open it so you can pour the gas you get gas all over your hands.I guess that sealed system sure does prevent fumes from escaping the can....until it fails and adds all the fumes from all the gas evaporating as well. Another well thought out plan by either bureaucrats, idiotic elected officials or a combination of both. On top of it all, you're out the cost of the can and the gas!
The problem with these gas cans, they are sealed up enough that they expand until the seam starts splitting and the gas spews out. I have had 2 of them that split down at the bottom and lost all of the gas. Third one that split on the top, so I found the split sooner.