After the far clip gets adjusted, you are most likely to want to see that it has happened or make a final adjustment now that the adjustment control maker is in view. Therefore the command should exit with the section selected. Adding something like the following does that.
// make the section selected after this is over. List<ElementId> selIds = new List<ElementId>(); selIds.Add(elem.Id); uidoc.Selection.SetElementIds(selIds);