As soon as the DROPOUTJEEP (DOJ) info was made public, Apple denied working at all with the NSA. The original form of DOJ was designed for close contact invasion - so you basically had get a hold of the device you intended to mess with - it wasn't a remote-use process. From the slides released, that was as of 2008, and at the time the NSA wrote that future editions might be able to be installed remotely. (Who knows what their capabilities are now.)
The point is that at least the initial edition of DOJ was not something that could take advantage of this type of backdoor via the internet or cell networks. Not only that: the NSA had been developing similar tools for use with various products from multiple companies. Apple wasn't alone, so while backdoors do exist on Apple products, it's a fair bet they're everywhere else as well, and could be interpreted the same way by someone looking in another direction if they chose to.
As always, no matter what device you use, your safest action online is to simply assume everything you say and do is seen.