Moving the pList around was never the intent of that pList being available. The tiles are cached in a location that is not publicly accessible for backup due to a licensing limitation. If the pList is moved, it will be looking for the cached map that isn't there.
To make it so you can move planned flights around, not cached basemaps, you could edit the pList file to replace the "downloadedUniqueID" alphanumeric code with "XXXXXX". This is a value that tells MapPilot that there is no cached basemap to look up.