The canary is an indicator of two things: Apple's attitude about these types of data demands, but also the terms of the court settlement that finally allowed the companies to disclose their compliance wth even secret requests. It is my understanding any such "canaries" had to be removed in favor of the reporting of ranges of surveillance requests.
From your linked article:
"Update 2: Ars Technica suggests that the disappearance of the warrant canary is a result of Apple following new Justice Department guidelines that permit companies to immediately publish ranges of surveillance requests — so long as the figure reflects a combined number of FISA requests and NSL requests. In other words, Apple may have received NSL requests, but not FISA ones (that does not necessarily explain, however, its decision to remove the section 215 language).
Apple, in those last two Transparency Reports since the court order allowing the comany to report the number of Surveillance Requests, has reported they've received in the range of "0 - 249 requests". Note, that still includes zero as a number. However, even if they receive a request, without your private key, such a request will return not much more than the proverbial name, rank, and serial number, and a gigabytes of 128 bit indecipherable gobbledegook.
Here’s a vulnerability listing I found:
http://www.cvedetails.com/vulnerability-list/vendor_id-49/product_id-15556/Apple-Iphone-Os.html
A blanket statement that 128-bit encryption is “unbreakable” reveals not much knowledge of encryption or disinformation.
Everyone should be mindful that NSA has publicly disclosed that one part of their strategy over the years has been sophisticated disinformation projects to make people think that insecure methods are secure, or that NSA does not have the capability to see their data.
My point with the telco non-disclosure court orders is simply that we see a precedent for NSA issuing such orders: we would not know then the full extent of all companies who have been issued such orders, because they may still be secret, and the company would be ordered to lie to the public and be granted full retroactive immunity for having done so.
If one does not know for sure that something is secure, it is wise to err on the side of caution.