I wouldn't touch the CSST with a 10-foot pole. It is thin-walled, and any clamping method would risk puncturing it.
I would ground the chassis of the appliance, just as I might any large metal appliance whether it ran on wood fuel or steam!
The pipe only needs to be bonded at 1 place, usually this is at the meter. If it is bonded there the entire system is attached to a grounding bond and would be legal.
The gas pipe is bonded to prevent it from becoming electrified by a short. It cannot be used as a grounding electrode but the grounding electrode system needs to be attached someplace after ...
Don't remove earth-neutral bonding unless you are sure both neutral and earth have genuine, quality separate paths back to the main panel.
Dirt is not a genuine, quality path. So if the only path back is via dirt using grounding rods at each panel, you need to hardwire a ground wire. Ground rods are for returning lightning, not human-made current.