Power Amplifier theory about car burglaries

The original Nick Bilton Style piece in the NYT has been picked up around the globe, not too many people offering up competing options for store-fob-in-freezer. Well, I ordered a couple blocking pouches (the sort of thing people put their phone in, or a passport, or one of those credit cards with NFC), and tested one by bringing a known working keyless entry remote near the locked car while in the pouch. The car wouldn't open. Presumably, if you store your keyless fob in a similar pouch when you aren't actually accessing the car/driving around in it, that would defeat any power amplifier based attack.

ETA: You might enjoy reading this description of an attack using wireless (and wired) relays.

http://www.isoc.org/isoc/conferences/ndss/11/pdf/2_1.pdf