1. Did that someone break any Law upon discovery of this (Based on country probable geolocation Laws exist for digital)?
I dont think the person broke any law. You are free to make guesses and if it turns out that your guess brought up a wallet that has assets in it, its not your fault. All you have to do is delete the guessed words that brought up the wallet, because it is not your own. This is just the right thing to do on a normal basis.
2. Is he allowed to spend it or transfer to another wallet and sold it
Such person is not allowed to tamper with with the asset found in the wallet, it is not his own.
3. Technically on bitcoins perspective anyone control the keys or able to sign a message = own the bitcoin (Is this somehow exempted?)
I think this is exempted, the owner of the bitcoin didnt drop the seed phrase carelessly. He went about guessing phrases, which he were not supposed to do. Since it was a deliberate attempt from that person to guess phrases of wallets that might have assets, it will be considered stealing if he claims those bitcoins.
4. Does he own now the bitcoin assuming the owner is probably dead and he can sign a message?
How would he know if the owner of the bitcoin is dead? Since there are no facts stating that the owner is dead, the bitcoin doesnt belong to him. Even if the owner is dead, the bitcoins are not his. Touching it will make you a criminal.
5. Is he fortunate or like win a Jackpot or just place himself more in danger upon discovering this?
He is not in any danger if he can move the coins around without taking it to centralized exchange. Because you cant trace him, the owner know nothing about the person. I dont even consider it as a jackpot, because he is stealing and hurting someone else. Hitting a jackpot doesnt have to be stealing from someone else.