Perhaps. I can't think of why they ultimately decided not to move forward with it, but here we are.
They dropped the murder for hire charges because discovery would have.. discovered the FBI doing very very bad things.
I doubt that's the reason. It could simply be bandwidth reasons as another commenter in the thread implied.
Prosecutors do not work for the FBI, and the FBI has no say in who gets prosecuted nor for which charges.
Prosecutors work with, not for, law enforcement and generally do what they reasonably can to maintain a good "working relationship".
And you don’t think the prosecutors consider the interests of the FBI when deciding what to prosecute? In cases where they want to use FBI evidence and probably want ongoing cooperation of the FBI for future cases?