Well if you can call USD, CNY, GBP, TRY,.... and the rest of more than a hundred fiat currencies being traded in Forex markets commodities then you can also call bitcoin a commodity.
Strange how Satoshi described Bitcoin as "peer-to-peer electronic cash", but in the post mentioned in OP called it a commodity.
After all bitcoin was designed as digital cash with the coins circulating from address to address which is also part of the security model as i understand it because it makes it even more pointless to search for hash collision on a public address as the coins are always moving and are not supposed to sit on an address for long period but move between single use address which also increase anonymity.
Who said that coins are supposed to be frequently moved instead of sitting there for years? There's nothing in Bitcoin's protocol that could incentivize that. The only reason to move coins to new address is if there's a protocol upgrade featuring new address format, which doesn't happen often.