The article did not state that the wallet belongs to Nakamoto and it is still under investigation and they do not have a concrete evidence that Nakamoto indeed owns that wallet, we never know but maybe it is under one whale in the past who suddenly have a need to sell his shares it is still under investigation.
who has 500,000 or more Bitcoins ??
This thread will give you some interesting names of potentially very rich people owning 6 figures of BTC:
https://bitcointalk.org/index.php?topic=321265.0The thread was closed because apparently it was inaccurate, but still, you should research these names, probably some of these people still got 6 figures.
Personally as far as this case goes, it could be someone that Pirate Roberts trusted. He could have left this person a backup of the bitcoin keys in case he went to prison, or did FEDs recover all of the coins? maybe lost Gox coins? Who knows. If they aren't super early mined coins then saying it's satoshi it's too much of a stretch.