Hey hey hey, let's not be mean. It was pretty ballsy of him to join.
What you want to do is this, as far as I remember. Set the event to check, and in the event commands, make it do whatever you want, then set a switch to turn on. Make sure the switch isn't being used by anything else. Then, make a new page. Make it so that it requires that switch to be turned on. Then, leave the commands empty. The chest is now permanently inactive.