They that have pow'r to hurt, and will do none,That do not do the thing they most do show, (1-2)
The first view we get of the powerful people shows them as isolated in several ways. The first thing that makes them seem isolated is simply the fact that they have power. If you have power to hurt others, this often (but not always) means that you are above them in some way—either because you are more highly placed in the social hierarchy, or because you have some special physical strength. All of these factors separate you from the people you can hurt. The second thing that makes the powerful people isolated is the description of them at the end of line 1 and throughout line 2, where we learn that they keep their true selves hidden inside them. So you could say that these isolated people have their true selves isolated within them.
Who moving others are themselves as stone, (3)
In this line, we get the same sense of isolation that we got from the end of line 1 and line 2: that the powerful people's true selves are hidden within them. It's still anyone's guess whether this is a good thing or a bad thing.
They are the lords and owners of their faces,Others but stewards of their excellence. (7-8)
Okay, not that we want anyone else to be the lord of our face, but we certainly don't want all our friends and family to be our servants. That's just awkward. And it sounds kind of lonely to boot.