My dealer ordered a new ECU for my FR-S to be installed Tuesday. I guess I'll play guinea pig and see if they've figured out a way to prevent immobilization.
There are other issues my FR-S is experiencing (A/C chirp, idle chirp, rear deck tapping) that they will be trying to fix, so I figured I'd get the new ECU, too.
It took them a few days to receive the new ECU; apparently, there was a redesign in effect (I assume due to the issue described in this post).
At this point, I'm not driving my FR-S at all. The tapping, rattles, and chirps are annoying, and, in my experience of having a different car bought back and receiving a settlement on yet another (I've owned over 10 cars in the last 15 years), it's best to keep the miles as low as possible on a car (if possible) you're experiencing issues with until a settlement is reached or the issues have been resolved.
In the meantime until I can get my FR-S fixed, I'm rekindling my love with my motorcycle.