The camera is initialized, just differently.So why would the M3, with AP2.5, not "intialize the rearview camera?" Or does this imply that initialization for that model is not required.
One possible interpretation if the above quote is correct is that Tesla won't be using the rear view camera on the M3 for AP functions. I hope this isn't the case!
Standard code on HW2.0: poke at MCU to ask it to initialize camera for us (done as generic camera initialization method)
Model3: there's no old-style MCU, the vision thread initializes the camera when it needs it.
HW 2.5 S/X: call a special script to initialize the camera since apparently asking MCU no longer works (or no longer desirable.