Based on the example here: http://help.arcgis.com/en/webapps/sharepoint/help/index.html#//015900000009000000 I do not have the Latitude/Longitude selection in their respective dropdowns on the Coordinate Fields when I attempt to create a new ArcGIS Location column. When I select the column type as an ArcGIS Location field the latitude/longitude dropdowns appear. But they do not contain the same selection fields as the example.
The sample data we used in that example had coordinate fields named "Latitude" and "Longitude", and that is the only reason they appeared as such in the drop down menu. The coordinate fields in your data may have names such as "X", "Y" or "Lat", "Long" instead.