The idea, I think, would be the analog of throwing thousands of dollars from a bank robbery into the street. The stolen bills can be identified by their serial numbers, but if law enforcement tries to crack down every time they see one of those bills pop up, the actual thief will be buried in the noise.

In Bitcoin land this is both more feasible and more complex at the same time -- it's very easy for a poorly planned version of this to make the thief no harder to identify, and even a well-executed version requires vigilance in the future to avoid betraying the identity of the thief vs. the identity of one of the giveaway recipients.

I suppose he could pose as the "winner" and claim ignorance, although I'm sure there's much better ways of laundering via a Mixing service [https://en.bitcoin.it/wiki/Mixing_service] or something similar.

Presumably he will send some/all of the coins to himself (plausible deniability).

Or maybe, you are right, he is not directly attempting to launder, but just "creating noise" in the block chain to make it hard for investigators to trace the stolen coins.