The biggest hint is the perfectly lined up timeline:
The last time Satoshi was involved in Bitcoin was around January 2011, Silkroad launched in February 2011. So if DPR was Satoshi, this would explain why Satoshi suddenly backed off from the Bitcoin development, he was too busy developing and running Silkroad!
This is the only thing that makes slightly sense. With everything else you are mistaken I guess.
Nothing points to nakamoto being American. Also I'm pretty sure that Ulbricht does not have the technical skills needed to invent and develop Bitcoin.
Ulbricht however once said that he is not the original founder of Silk Road but that someone handed it over to him. What might be true (although not very likely) is that nakamoto is the founder of silk road but handed it over to other people later.