Structurally overweight, or performance limited by runway/weather concerned that day?? Ski flight?? Route to be flown?? En route winds back from 6+ hours away??
There are many variables...
In around 2006 I took an Easyjet flight out of LPL. After a short delay post boarding, the captain announced that an error light was indicating that one of the overwing exit slides was faulty. Long story short, they couldn't be certain that the slide would work in the event of an accident, which reduced the maximum passenger capacity of the aircraft below the number of passengers on the plane. They offered £100 to people who were prepared to rebook on a later flight.
I'd be very surprised if this aircraft was structurally overweight, even if it was laden down with heavy ski's- Liverpool to Geneva is a short journey for an A319. There's almost certainly much more to this story than is indicated in the article.
If it's true that passengers clubbed together to increase the compensation offered for volunteers to leave the flight, then this would be very bad
PR for Easyjet. They seem to be trying very hard to differentiate themselves as a 'value' airline, rather than a 'budget' carrier.