You can put an iPad into airplane mode and then go in and turn on WiFi separately.
But there's a whole can of worms they probably didn't want to open. Not in the least the issue of caching and copyright. This will be even more of a problem with allowing people to use their laptops rather than an iPad which is already hard to get data off. Plus cabin crew would end up being tech support.
Is there anything they do to stop iPads from being disappeared by passengers? I guess an RFID tag and a reader at the aircraft door should do the trick.
First comment from the article:
This will never replace the experience provided by a system installed in seat.
This person obviously hasn't experience the latest and greatest QF IFE system on the A380s!
Even the SQ ones he alludes to as being great couldn't hold a candle to the interface, video and audio quality you get from an iPad.