As long as the wiring is good for 20A it's fine. Also if you break open a 15A recepticle a lot of them have the 20A contacts in there as well since it's the same unit just with a different face.
When a breaker pops the switch moves to the middle, to reset, you have to turn it all the way off and then back on. If it's in the middle and you go straight to on then it's just springy and nothing happens, and it moves back to the middle.
So yeah, ruins the joke but nothing's compromised here.
A genius solution! (startrek.website)