About that whole thing, the ENTIRE situation (instead of just "OMG they turned off grand finals") goes like this:
They wanted everyone out at 9 to set up for Bang the Machine. From 9 to 9:10 they were telling everyone to leave over the mic, and they even flashed the lights a few times. Nobody playing or watching GG noticed - I know, I was one of them. :^) Around 9:15 Evo staff started coming down the row of BYOC monitors turning them off, and by the time we realized they were coming they were too mad to be intercepted and reasoned with - I know, I tried. :^)
There was no way to tell our tournament apart from a large casual setup, either.
From our perspective, wtf they turned off a tournament. We didn't tell them it was one, we didn't notice them telling anyone to leave, and we didn't look at the Evo schedule to figure out they would probably be telling people to get out at 9.
From their perspective, wtf we hadn't noticed in 15 minutes. They were well within their rights to turn it off, since we had gotten an extra 15 minutes. They have been nice to side tournaments in the past, as well.
I talked to the Cannons afterward, and the arrangement from now on is something like:
They'll be adding to the Evo rules a section like "we reserve the right to turn off ANYTHING when the schedule says people are required to leave."
We can look at the schedule (our first mistake this year), look at the time, and tell them we have a tournament running. They will let us finish whatever match is going on when we should be leaving, but we have to leave after that.
The people I talked to stressed how important side tournaments and the community are to Evo, but they also stressed how important the schedule is when thousands of people are involved. (^.^)