There is a possibility about that but destroying the private keys of those wallets does not make any sense or it can make sense if it is lost forever.
Of course it makes sense. If he truly wanted to disappear, he must have destroyed them. Otherwise, if one day he spend it, he could be tracked. Of course he thought about that and destroyed them
If he wanted to accumulate BTC he could just mine them later on, in 2010, 2011 whatever...