No. I would simply retain $40K from those recovered from Chen Jianhai, and convert that to Singapore Dollar and send back to my friend.
If later found out that the recoverable stolen funds exceed $140K in total, then it will be my personal liability to deal with Bitcoinica directly. In any case, AurumXchange shouldn't be holding the funds forever. $40K is only a small part of my total liability (this becomes my "liability" to Bitcoinica once I recover full amounts from Chen Jianhai), so there's no reason to not trust and co-operate with me when I can deliver my promise of the $100K and 20,000 BTC.
In the situation you are in
I forbid you to retain anything at all as long there are liabilities to Bitcoinica customers. Your personal liabilities come second and I personally don't care.
In case you are behind all that (And I want to keep this option open) that move is just a smart way of circumventing AML-investigations. You also wouldnt be responsible to prove the legitimacy of these funds anymore. Comparing the total amount of returned vs. stolen funds that leaves still the possibility of you making a profit in this hack (hypothetical situation)
Also moving the risk of goverment seizure of your friends funds or lengthy unblocking procedure to Bitcoinica customers is just unfair. We as customers were not involved in money laundering YOUR FRIEND WAS so he has to take the risk!