It's not about whether it's 'breaking the rules' or not. In F1, if you pass the tests, you're legal.
This is about trying to get the FIA to make the tests more stringent to better enforce the 'spirit of the regulations' so your opponents have to change their design, hopefully in a way that hurts their competitiveness. Red Bull are extremely familiar with that game when it comes to flexing wings...
Heck even if it doesn't directly hurt the competitiveness, in this salary cap era you'd still be causing them to spend precious time, resources and opportunity cost to redesign the wing in question, so it's still a win.