Bill Boddy - I'd been amazed that all of the focus had been on Red Bull's rear wing, given how obviously the Mercedes' front wing was flexing in previous races... This on-board from Portugal illustrates it perfectly
I think it's because the bit that's moving are the "fingers" of the wing, the main plane itself is static from what I could tell - I don't think those fingers are even subject to load tests - they're all on the main plane. (and Redbull are doing the same thing)
Whereas the redbull rear wing (I've not seen the Ferrari one) - the whole thing is deflecting including the parts that are load tested, so they're clearly circumventing the test.
I'd also imagine that this, like the alleged fuel flow meter circumvention, isn't a case of Merc sour grapes because they didn't think of it, but because they thought of it, but didn't do it as they decided that it would be cheating - which it is.