If the instance is shut down from the server side then the user should get a nice little error message as it cannot connect. They then know something is wrong and either:
1) Work out that they had forgotten to move back to the live system, hopefully before entering any real data into the test system in the first place
2) Blame IT and say that something is broken, which when investigated will quickly lead pretty much the exact scenario minus the two weeks of live data in a test system.
I'm not exhonorating the user of any blame, I am simply pointing out that by shutting the test instance down properly when testing is not actually needed, it would have prevented this problem. Continue to downvote away if you don't like it.
Biting the hand that feeds IT
