A clarification:
If you share just the .BGL without the .XML, it will be removed by the Control Panel, because it's considered to be orphaned. This is normal, to prevent the exclude folder to become a mess very quickly.
So, if you want to share the exclude file, you should provide also the XML that will stay in the Exclude folder, one level above the scenery folder that contains the .BGL. However, you don't have to do that, since the parking customization can recreate the XML automatically from the .INI file.
This can be done by opening the parking customization for that airport, and deselect/select any one parking that had the Exclude checkmark set. You can do it by changing anything else, but this is the easiest one and the easiest to remember. This will trigger the parking editor to create the Exclude XML, which can be then compiled into a .BGL.