This is most definitely a scam, and I have proof.

Yesterday, he pointed out in a support request that about 230 BTC in this address was his on behalf of his customers:
http://blockexplorer.com/address/16k6KeqY13MEwXCKa6uMWvsg7Bmqq1TzXb

Thus far:
35.5 BTC haven't moved
At MINIMUM 78 BTC was change that is still in his control (if it was the other way around, it was 150)

That's 113.5 BTC that the thief decided to just leave. Yeah... BULLSHIT!