Depends pretty much solely on the language of the policy, I'm thinking. If it was an all-risks sort of policy then I'd bet Wynn's probably got a case. Having a deal in hand at the time seems to ice up the valuation part of the problem.
How did he accidently place a tear in the painting?
There is art where I work. A few years back some genius with a mail cart accidently ran in to a painting. Didn't tear it, just scratched the paint. He had to explain that to the curator. Ack.