We do not know for sure. But if I were him, I will not show myself to the public because that can make me in danger. After all, many third parties want to know more about me. I do not want to show myself here too, because I know that in this forum, some people still secretly watching the forum to find out about satoshi nakamoto.
I think Satoshi Nakamoto already prevents the hacker from hacking his wallet by using many things security layers that we might do not know. He is the creator of bitcoin, he knows the code, so I am sure he knows what he needs to do to secure his wallet. The bitcoin that will be sold at the market will come from the bitcoin that already gets hacked on the exchanges.
Satoshi could do whatever he wants to prevent, there are few other methods hackers could use, but in the long run it will be broken without a doubt. How? Well if satoshi is already dead, that means he can't keep up with the tech of security and he will not be able to defend it while the newer high tech will make sure that hackers can get in easily, maybe it will take 10 years of tech development to reach there, maybe 50, maybe quantum computers can become reality one day and that will hack it, no idea what will happen but in the end we are talking about something that is guaranteed no matter how much time passes.
Secondly if it is a group and even if one person dies they get another so they never really end, it will always depend on one great hacker to be better than them and secretly get in, it is not "impossible", sure it is very difficult, but not impossible.