The pass would have been legitimate if they had been racing, but they weren't. The rules state (article 40.13 as shown above) that if the final lap starts under the safety car it will come in at the end of the lap and the cars will proceed to the finish line in their current order. It's actually simple and clear. So Ross Brawn didn't know the rules, whos fault is that?
I don't agree. They were racing, otherwise they all would have cruised to the line! Green flags and lights means race on to any driver.
You're right, it's simple and clear if the safety car was still deployed, but it wasn't. That was the mistake of the race director.
You can't say that Ross Brawn doesn't know the rules! If there was doubt, I'm sure someone in the team could back him up too. The new rule for this year allowing passing beyond the SC line made the pass possible.