Good question. Also, the wing could have been designed to circumvent changes in weight loads, for example.
What I'm not clear on is whether the FIA can change the method of testing. We know they can change the tested weight, but can they change the direction or application points without a rule change?
The teams have to provide a jig for the purposes of checking for flex, which means a new test might require a new jig and surely you can't just spring that on them at the last minute?
As for Flavio, there's no way of knowing that he's tweeted something he has inside information about, or just a 140-character-limited version of the rumours discussed in this thread.
There is an Italian rumor going around that the FIA will change the loadpoints for the test (ie instead of hanging weights near the endplates they will hang weights at the rear edge)
It's a rumor as of now, I haven't heard anybody "officially" confirm it.