I always think to myself, "Why should anyone take what the Feds say as truth?" Their record for truth-telling isn't exactly stellar .... :-)
If Dong is a mirage, and still in China, that opens the door for them to track him down and 'Epstein' him. If they acknowledge him, they must acknowledge his intel. And THAT ain't happening.
There may be no other person EVER that the derps AND China wanted to disappear more than him. Well, maybe Trump.
This gives new meaning to The Hunt for Red October.