Not in this case [1], or rather, not always. And if you consider where the term arose (canaries in mines), it's really an issue of state more than it is absence. If the state of the canary changes it's cause for alarm.
In this situation, warrant canaries (or maybe an NSL canary as the case might be) is a subtle indication that everything is no longer in a known-good state and something has been compromised.
Although given some of the comments by danielweber, I'm increasingly less inclined to believe this was a canary. Developers throwing in the towel might be a more plausible situation, no matter how disappointing that may be.
In this situation, warrant canaries (or maybe an NSL canary as the case might be) is a subtle indication that everything is no longer in a known-good state and something has been compromised.
Although given some of the comments by danielweber, I'm increasingly less inclined to believe this was a canary. Developers throwing in the towel might be a more plausible situation, no matter how disappointing that may be.
[1] http://en.wikipedia.org/wiki/Warrant_canary