An argument should be made the damage was caused by the other boat not an “act of God”.
The argument would be that the mooring was in good shape, adequately sized, and no part of the mooring chain, pendant etc failed. The mooring broke free from the bottom due to the wave action and tidal surge caused by the storm. No one could have reasonably predicted the out come nor have reasonably prevented it, therefore it is an "Act of God" and we're not liable for the consequences of an "Act of God."
If some part of the mooring failed, the chain broke, a shackle failed etc. then a case might be made that it was inadequate inspection and maintenance caused the boat to break free and damage other boats. We don't know whether those facts might be in play or not.
I don't want to seem insensitive to the OP plight. It sucks to have your boat damaged. Been there done that, had my boat blow off the jack stands in a storm to the tune of $15K in damage. I had made the choice (with the bank's influence) to carry damage insurance, so I only paid a small deductible. My boat was the first domino, with 2 other boats coming off their jack stands. To the best of my knowledge they did not file a claim against my insurance. If they did, my insurance company didn't tell me.