Re: These new indictments could help Assange ...
"As I understand it, you can't apply for extradition on the basis of one charge and then throw a bunch of additional charges at the subject once you've got your hands on him".
As I understand it, you are - quite understandably - under the misapprehension that the US authorities give a flying fuck about any law, constitution, treaty, agreement or moral principle that doesn't give them what they want.
They don't.