No, I'm not sure, but it does physically match the cards and readers in the article.
With no foil, the badge is read at 3-4".
With a single slice of foil ~18"x12" held in front of the sensor, the badge is read at ~1" (a noticeable reduction in signal).
With the foil folded in half and the badge in the fold so that it forms a single layer on both sides of the card, it was effective (could not read the badge).
With the badge in an aluminumized mylar antistatic bag, there was no evidence of a signal reduction (read at full distance).
I would theorize that Maxwell hasn't failed us, but the signal is weak enough that the foil attenuated the signal sufficiently to disrupt reading. The RFID reader works by modulating the sensor tuned loop by detuning on/off, which is going to be a pretty weak signal.
