My 2 cents. I say that Kevin keep the trade. I then say press charges on Kevin for reciept of stolen property. Its clear that he knows its stolen, now.

If I sell you a stolen gun so you may protect your home and you use it to shoot an intruder, do you think that you wont be charged with mere possession of stolen property? Of course you would. If you bought a stolen car and didnt know it was stolen and you got stop by the police do you think you would be going to jail? Of course you would. Even if your only the passenger. The law (in the USA) doesnt care if you knew the item in question was stolen. It only cares that it is merely in the possession.

So Kevin, I have some questions for you.

1) If your car was stolen and resold 10 times, would you still want your car back?
2) How long of a jail term is worth the btc you bought?

With that said, MtGox does have some culpability. You might look into getting a layer, but most layers will want payment upfront.

If it were me, I would have little issue returning the btc, tho it might be painful, I know I would want my stolen items back.