Jeff Mercado is correct in saying:
He could still "see" the question since he didn't navigate away from the page so he clicked again (and again and again).
When you delete a post, it doesn't immediately become inaccessible to <10k users. They see the same screen, but with a faint red background. If they try to refresh the page or come back to it later, it disappears, but not instantly.
From the revision history, it looks like that's exactly what happened. Intuitively, when you delete something, it should disappear. However, the user being new here, was not aware that nothing is ever really deleted and was confused that he can still see his contents and so kept clicking again and again. By the way, this feature of allowing users to see the deleted question until they refresh is status-bydesign.
You always have the ability to delete your questions and answers (and by extension, undelete it). It's true that you're not allowed to see the deleted question when the page is refreshed, but you're allowed to see your own deleted answers if you know the link to the question. So the ability to undelete is useful when you delete an answer and then improve it and undelete. It's probably easier to code and maintain undelete rights across both questions and answers the same way. The system only makes a check to see if the post can be deleted (i.e., is not accepted or has no upvoted answers)