It's not that the early 2012 chassis can't be braced, they can, quite easily, it's all about access, as the bodywork needs to be removed to get to it, and possibly the engine too. This is a huge amount of work.
The factory were aware of the problem very early on, I've heard that at least one early dealer demonstrator chassis broke, and they used small gussets to beef up the chassis on 2013 cars, although I don't know of any breakages yet, this was super ceded by proper triangulation for the '14 model year. Incidentally, as far as I can see, this is the only proper triangulation on the whole car, it seems the factory designers decided not to triangulate the chassis at all for some reason?
