He doesn’t want the judicial branch to know who he is spying on. I thought that was obvious.
That is not obvious, and that explanation doesn't make sense.
The only thing that is obvious is that the spying is being done without the intention of prosecution of people in the U.S., since any information collected without a warrant cannot be used as evidence.
All I can guess is that the information is being collected for covert action against the people outside the U.S. Locating them, dragging them out of their houses, and killing them on the grounds, etc.