Famous line from movies(I cant do the accent in type): what we have here is failure to communicate. I am a Steward and have worked control on many instances. It is my favorite part of the job. I also dont like to point fingers and want to be productive here.
The drivers did nothing wrong and it appears that Control thought that the green was displayed so that the call to all corners to drop flags was relayed(there are many tracks where due to angles, etc, Control cannot see all the actions of the starter). Since black flags were eventually displayed, I must also assume that something BIG was going on that justified stopping the race. Or maybe Control just wanted to correct the error. Two wrongs dont make a right, IMO.
I'm sure that this one will make the stewards seminar.