Impossible with QR...?
Surely an Android app with a QR scanning library could grab a "username" and password from a QR code too, then configure the WiFi adapter in the same way? Even if the usernames / passwords are generated per-person, the QR could be displayed on a screen.
I'm not trying to knock the team's achievement, as I think NFC is a useful technology and they've shown plenty of ingenuity, but describing something as "impossible" is usually asking to be proven wrong :-)