Such bullshit. They definitely initialize the camera in the background. That is how you are able to simply swipe to your camera view and it is immediately active. Otherwise you would get a slight delay while the camera is initialised. What they are calling a bug is that the user actually saw it it rendered to a view... Have no doubt - this happens on ALL apps that dont have an apparent delay on switching to a camera…
This may be true... Previous versions used to take an age to load up the camera screen/swipe action was blocked (assuming the initialising process). So looks like this may of been their attempt of fixing the UX
They have been doing it for as long as I can recall. Its common practice. From my perspective, the problem is that they arent acknowedging they do that - they are instead saying its a bug that they have fixed - but you can be sure they are still preinitializing the camera...