It seems perfectly possible that Francois and Noizant had their eye on whatever funds were potentially unclaimed when they acquired Instawallet and it's fund pool from Jav.

When the 'hack' happened Boussac stated several times that they did not know if they'd 'be able' to pay off the larger wallets.  The inference which was probably supposed to be drawn was that some funds had been stolen by some party external to their group of organizations (bitcoin-central, paymium, etc.)  Another possibility is that they simply did not know what their take would be in the unclaimed wallet windfall and if they would be happy with it.

The possibility looks pretty strong that ~davout (with or without the knowledge of ~boussac who seems technically incompetent) decided to do his 'civic duty' and teach the community a lesson by appropriating at least one large wallet.

~jav's approach to trying to communicate the lesson was to warn in no uncertain terms on the front page of the website that Instawallet was to be considered to have limited security and was for small amounts of BTC only.  Somehow along the line that warning got misplaced in a re-design after ~davout/~boussac got a hold of the service.