Seems a bit biased in places. One of the example sites has a big scary red X next to "Deleted images are not really deleted", despite that being an important feature for any site that lets users delete their own content. It's one of those tradeoffs you make where you trade a tiny fraction of risk (e.g., that somebody might break into your system and steal the exact cat photo that one high profile blogger was embarras…
Since all Twitpic does is hosting public pictures for Tweets, I would assume as a user that if I click "Delete" then the pictures would be… well. Deleted. Having a short period to rescue the picture from a back up would be acceptable.
I don't understand your example with the "high profile blogger".