Of course he's gonna ask for it to be closed.
Let me make it a rule so i can lock the topic if i know someone has nailed it, any decent person wouldn't mind that.
Don't open a topic i've closed.
EDIT: I added this rule, i think this is a fair rule:
10. If the section admin or an admin knows a challenge has been done by someone they have the right to close that topic.
If someone has done your stunt you can take contact with the section admin and request a close but you have to show the stunt as proof.
The creator of the topic has the right to PM the section admin and ask for the topic to be re-opened if they want that.