I do believe that Satoshi is not really in danger the fact that his bitcoins are not moving doesn't really mean that he is being held by the authorities it just mean that we have a stable sum of btc being stored at a wallet whose owner we know will never sell it personally.
That's why the price won't ever fall beyond a certain value.
Even if Satoshi still alive and definitely has the private keys to those coins, I doubt he will ever move his bitcoins due to the risk to reveal his identity and could affect the price, so it would stay there forever to preserve it. Since bitcoin protocol so safe, no need to worry about it, whoever manages to access the private keys will be traced and can't escape freely, yes he is in danger.
I do think that the authorities already know about his identity but rather it's not safe to reveal it.
But who knows. ?
Maybe in the future we will hear from him.
2/ the person who have btc don't move it because there is a risk for is identity.
Those Bitcoin don't need to be moved. If I was satoshi, I would have mined bitcoin in another anonymous wallet that no one knows about it. I would have planned that I will never touch the bitcoin in Genesis block and the wallet that I disclosed to the community.
I read a topic on nonce of bitcoin transactions from satoshi. I did not save that topic so can not give you a link now.
A hardware wallet would be nice though. Or a paper one.