I'm not sure if anyone has TRIED to fxz back to .886. But I'm pretty sure that it would be a disaster.
This update has made major changes to the radio kernel.
Consequently, if you do fxz back to stock, I'm sure that your system would either not boot up, OR be such a cluster that you wouldn't be able to progress to ANY update.
In spite of that, this IS an OTA. Whether or not it was a 'mistake' is irrelevant. Verizon sent this over their network; therefore, it will be supported by future updates. Since the update has been captured from the cache and not altered, it should be safe to update in the STOCK RECOVERY, this shouldn't matter as I think there are commands in this phones stock recovery that are not supported in CMW (probably just renamed on this phone).
Short:
CANNOT FXZ back to .886.
WILL be supported in future updates. (I'm not the Verizon CEO so I can't promise this.)