Even if the creator of the Bitcoin Satoshi Nakamoto does return, I dont think its going to affect the rate of the cryptocurrency. While the market is expected to grow and stabilize within the next couple of months, its probably not a lot to do with the developer. Moreover, I think this news is fake because why would the maker or makers return after such a long time?
I am not sure about this is true or fake but another news which I read someone pretends that he is satoshi nakamto but he proved that he is lying and as you said the returning on satoshi is not going to change anything but may built trust on people again which can increase the more people to enters into the market.
For me everything can change if it becomes a true news that Satoshi is back because suddenly everyone will be back in the market and buying will begin in large . This will build confidence in the market as Satoshi would definitely the point who can change the course from here.