First of all, I think governments have tried to find him but couldnt or may be found and never revealed. I may be wrong but if governments tried to find someone then they will. Even if they have found and have hold on him, I dont think he will do anything against his will.
Exactly because nothing is impossible to government now specially US who has all the resources to use in anything they need to find.
Satoshi being a tech person can be find easily by the CIA and FBI so maybe government already knew satoshi or maybe under their watch,but doing anything against his will?well that is another thing mate .