he is talking about a different kind of lost coins not coins that are not moved. there are in fact lots of bitcoins lost because of reasons such as forgetting an encryption password to a wallet or a lost wallet because of hardware failure, and generally things like that beyond recover.
there is actually a topic in this board about it where people comment on it with their lost coins. i myself had a brainwallet with 0.01
BTCish which i forgot the password to

I know exactly what he is talking about. Read this post again.
I think number of unspendable bitcoin is more than this because there are also lots of addresses which contain bitcoins and nobody have access to it, like addresses of wallets whose password were lost, known addresses of satoshi etc. However nice listing...
It could be anyone, but let's take Satoshi as an example as it gets mentioned here. Him not moving his coins doesn't mean that he has no access to his wallets/private keys anymore. It's very simple to just assume so since these coins haven't been moved, but there are good reasons for him and other early adopters not to touch their coins (yet). It's not just a few thousand $$ worth of Bitcoin that we are talking about. That's what I tried to point out.