Not a chance. You do not understand insurance. I do. The carrier has sold its risk into the reinsurance market. Probably owned by 10 EU banks with billions of risk and hundreds of millions of annual premiums. No one cares about the loss. It will reduce the profit from the portfolio by a microscopic amount. A rounding error.
I also know the insurance business. Unless the guy has insurance for war related damage, the insurance company is not going to pay.
As you must know, insurance companies often deny claims which are clearly covered. And what court is going enforce coverage in a situation like this? The guy who caused the yacht to flood could be considered a terrorist. That’s also probably not covered.
The guy who flooded the yacht admitted why he did it. He crossed the line from vandalism to subterfuge.
Consider this. If not for Russia invaded Ukraine, would this guy have flooded the yacht? If the answer is no, it’s an act of war.