Yeah I don't think that is true, why then did Vice.com pull the photo so fast after it was uncovered? Why not strip out the EXIF data altogether in the first place...or simply disable geo tagging on the phone. Why would he then even tell people he manipulated it...doesn't make sense.
The project is a great proof of concept, the chances this will get someone's stolen camera back is pretty slim. We have a similar project, but it searches for the data using existing search engine data. Only about 25% of cameras will embed the serial number, then when uploaded only a few sites will retain the EXIF data, or provide it through meta data. A few that keep the EXIF data or provide it in meta data include:
Flickr.com
DeviantArt.com
SmugMug.com
Picasa.com
Some of these sites strip out some tags. Some manufacturers have custom EXIF tags like Nikon which may store the serial in a "Serial Number" tag or a tag called "0x00D".