The signed message doesnt prove anything unfortunately. I also dont buy the whole hacked argument either.
I don't buy it either. However, it's plausible that the account is still under the control of the original owner. It may be an account farmer trying to rescue the value of his merchandise. Who knows. However, we should give him the benefit of the doubt. Perhaps a neutral tag is more in order in this case. At least with the new system, neutral rating's show up as a tally.