I have been using similar methods to update airports as well. Another technique for creating exclusions which can save a good deal of time is to simply select "Lists" from the tool bar, then "Scenery Objects". Click on "Select All" and "Delete". ADE automatically adds a small exclusion at the insertion point for each object.
Of course if you want to exclude only some of the objects then select only those in the list which you wish to remove. ADE will automatically move to that point making it easy to verify you have the correct object.
I have done more than a hundred of the ORBX Freeware airports using this method quite successfully. Saves a lot of time.
Hope that helps,
Jesse