The point isn't that those 50 Bitcoins are worth $14k, it's that he owns up to a million of them, and nobody is sure who he is or whether he still had control of those coins. This seems to prove that he does, unless blockchain.info is wrong.
> it's that he owns up to a million of them
We have no evidence that that is true, however it is widely speculated and believed to be so.
The speculation for that particular number is trivially falsified: It's based on assumption that all unmoved coins in the first year were mined by the system's creator (no justification is provided for this assumption).
And it is false, many other people mined during that time and lost keys (myself included).