Just an update:
I've been to the Kingdom several times since I posted this rumor and I took some time to do some snooping. I didn't speak to anyone or ask any questions mind you, I just tried to park in parking lots. I went to the Poly, GF, Contemporary, the Boardwalk, and the Beach Club (no Yacht yet). I was waved through with my photo ID every time. I also went to Coronado Springs, Art of Animation, and Caribbean Beach (not that I honestly expect an issue with parking at these resorts) and it was the same.
I am thinking this is more in the realm of uncorroborated rumor. That, or it was an extremely short-lived test.
On another note I wanted to point out my experience at the Poly two weeks ago:
My wife and I made reservations for Spirit of Aloha. When I tried to park at the Poly around 7 PM (on a Saturday) the lot was completely full. I drove around for about 10 minutes with about 6-7 other cars before I stalked someone to their spot. After dinner, we went into the Kingdom for a bit. Lines were long, so we just walked around. When I got back to the car around 11PM, the lot was half-empty. Food for thought: dining reservations have a big effect on the lots.