"insufficient evidence" = there was evidence but not enough to satisfy undisclosed criteria.
"bound by regulation" = no matter what the evidence was, conclusions were dictated by "policy"
"requires a process other than the doj" = there was nothing he could do about it
Indicting the president "was not an option" = he couldn't no matter what the evidence showed
My bottom line : he's covering his ass. I see one message loud and clear.... his hands were tied. And he wants out now.