All transactions are publicly visible, so everyone would know that it was now possible for someone to take bitcoins from people. Value depends on resale. Why would anyone ever buy a bitcoin or accept payment with them if they can just disappear at any time?
Ah, I read it too fast and missed the theft context regarding Satoshi's wallet. Thanks. Part of me hopes that in the not-too-distant future Satoshi will do a tiny transaction on his wallet just so all the speculation ramps up again and we get another wave of entertainment.
If that's the problem, you just say "this person had lax security" or "their computer was compromised." In the absence of real proof that will be the default expectation anyway.