That was certainly the excuse. But it is trivial for Apple to buy any patent it needs. I believe the real reason is that FaceTime and iMessage hook people to Apple platform and discourage switching to another one.
The patent troll in the case got a 440M award… and Apple had to spend a bunch of engineering time throwing out the already-working p2p implementation and rebuilding a centralized version… and you’re suggesting that this was all a mere smoke screen?