I've been involved in these situations several times, unfortunately, and there's no good way to do it.
Speaking for myself, it needs to be done face-to-face, no matter their respective locations. When it comes to DSR, they represent the elite that the sport has to offer, so locations probably had little to do with it. On the flip-side, of all the dismissals I've administered or been a part of, a high percentage of those resulted in comments like, "You had to call me in here for that?!". I believe that any professional in the position of having that level of authority should always be conscious of the individual's dignity, regardless of the situation.
Just my .02
Sean D