ArcExplorer is definately the route you should take.
There are a number of advantages to it:
1) The points can be imported very easily using the GUI.
2) If they ever do decide to shift to a GIS, the layers in ArcExplorer can be shared using Layer Packages or KML files.
3) The google earth interface is not as user friendly as ArcExplorer & you also have the ability to change to a number of Basemaps on the fly - ArcGIS Online (Imagery, Topographic, Streets) Bing and OpenStreetMap with 2D/3D rendering.
Lastly, if you yourself are an ArcGIS user, it will probably make your life a little bit easier to work with a format that is well organized and familiar to you.
Cheers,
P.S. At the Federal User Conference, esri announced there is going to be tons more functionality built in to ArcExplorer over the course of the year.