Essentially what you're saying is you found a private key collision on the Ethereum blockchain, and Ethereum would be broken as a result of it (since you are claiming you got access to someone else's ~$400k worth of ETH/ETC and could fuck them over if you are successful in liquidating it). If this was true, it would have a devastating effect on ETH and crypto as a whole. Pretty bold claim - would love to see the proof of it.