I do think that the stuff about having 36 days to return the 462 BTC amount doesn't look very legit (i.e. the hacker gains 1 month to "disappear to another country").
If the hacker wants it over and done with why wouldn't he just give it all over now and be done with it? Smells fishy to me.
From what I can see, so far the hacker hasn't held up on their end with the promise (the only tx to the agreed address is -
https://blockchain.info/tx/bfdedc91f7f909ad56733bbcffc75214ad49f96d362ae2fb69fb6b529173686a) which is about 100x less than the overall amount and 50x less than the agreed amount for the first split.