They don't have to have the flywheel running during a launch.

I don't think they run the landers at night on Mars anyway.
You could always auto reboot the computer after the flywheel spun back up.

Have you guys ever watched the comedy channels Battle Bots series?
There is a bot in the competition called Ziggo and it spins extremely fast yet it is very manuverable.

I don't see why it would be adversely affected by low temperatures I would think this would help it's operation rather than hurt it.

We know the cold kills batteries.

Perhaps it could double as a back up gyro as well.
It would offer some stability in windy conditions.