I'm not a computer scientist, so I can't dispute that directly. I can tell you, though, that there are lots of computer consulting companies out there which charge lawyers a lot of money for telling whether an image is genuine or has been altered by, or generated on, a computer. If they've been scamming my law firm (and the courts in which they testify as expert witnesses), I'd love to know about it.
Most people are not gifted in the use of these tools, yet. And it is usually pretty easy to tell amateurish digital images. However, these consultants should start branching into different areas of expertise, because sometimes (and it is becoming more often) you really can't tell the difference.