If Satoshi attempts to spend his coins, this might reveal his identity. Which in turn would increase a risk of kidnapping/blackmailing/torture/etc from anyone willing to get a share of his stash. Same applies to his heirs in the future. My guess is that he may have deleted all the keys to early coins traceable back to him, just to avoid temptation.
He could have mined a lot of cheap coins in 2010-2011, though, so he's probably not without a big reward.
He could have mined a lot of cheap coins in 2010-2011, though, so he's probably not without a big reward.