They're nothing alike. Suppose Silent Circle sent an email to all its users announcing that they would destroy the data on the server in 7 days. It's a good bet the government has accounts on most privacy-advocating web services, simply to keep tabs. That gives the government 7 days to try to get a FISA warrant, or if they think they can get away with it, unilaterally issue a NSL.
They would only be able to subpoena a few of the email accounts (or maybe a lot, but certainly not all), but that still breaks the privacy model many people assume given its advertisement as "secure" webmail.
Silent Circle didn't want to take the chance, and your hyperbolic parallel notwithstanding, they had good reason to do what they did.