Just in case it needs to be stated: innocence is a presumption, not a conclusion. It flows from the presumption of probity, fundamental to the Constitution, that the individual natural person is moral/good. It is this presumption with which religious fundamentalists, who are convinced that all men are sinners and need to be saved, disagree.
In any event, when it comes to an agent of government, the Constitution is not concerned with good or evil, but with the duties and obligations agents of government pledge to carry out in order to provide for the general welfare. This encompasses an expectation that personal interest is left behind and that, indeed, is why agents of government are paid.
That Donald John Trump apparently does not understand that is beside the point.
That said, William Barr is an agent of the United States and, if he has been given a mission that takes him overseas, rather than sitting in an office from which he can be summoned for personal meetings at any time, who can blame him for absenting himself.
Also, keep in mind that dealing with a narcissist is deceptive for the simple reason that his/her behavior tends to mirror that of the person with whom s/he immediately interacts. Large groups of individuals doing their own thing are disruptive in that they may prompt mimickry that upsets (remember Trump and the handicapped reporter?) We know that the narcissist projects; that he also mimics is perhaps less well covered.
We now know that some people are faceblind. So, how do they respond to people they know? Instead of going by visual information, the respond to aural clues and, very likely, touch. Indeed, the pervasive habit of people (especially males) shaking hands may provide a cover for a lack of facial recognition. (Does Trump’s long tie help him identify himself in group pictures? That a narcissist may be face blind to himself is perhaps not widely considered).