It's hard to see this as much anything but snake oil. While the technique allegedly allows you to target multiple models, it still requires you to know what adversarial model you're targeting before the fact. If the adversary sees there's visible artifacts they'll just change a few parameters or use a different model and be good to go none the less. In short, while this might be academically interesting, I can't help but feel that this is a futile field to work in. A good way to see why is to look at it this way: a skilled human can manually manipulate an image so that it isn't possible to tell that the image has been manipulated. It is then a matter of teaching the model to do the same, which might take time or be computationally prohibitive for now, but eventually it will be done.