A question of .... basic sanity?

Alright, so in the midst of looking up Miss Manners and Dear Abby letters to use for a lesson on giving and receiving advice (kindly stolen from Bob) I came across this letter.
http://www.washingtonpost.com/wp-dyn/content/article/2007/10/09/
AR2007100902200.html

Now, let me give you the gist if you're not inclined to read the actual letter. Guy is asked in a coffee shop to watch a laptop so no one steals it. He declines because the computer is behind him and he would have to swivel around and wait around until the person came back. The woman called him a no good dirtbag who would surely invite the wrath of Khan. Apparently he gets this response a lot when he declines to watch other people's stuff.
I have to wholeheartedly agree with Miss Manners - where's the logic in leaving your stuff with a stranger to protect it from strangers? Just me but I'd probably laugh in their face, pull a Josh and look them seriously in the eye and say, "Alright, but as soon as you leave I'm stealing it." But that's my bitchy self. I'd then snarkily turn around and continue reading. Then again, I've never been approached by this request ever so I could be blowing smoke.