It's mostly that it doesn't use the typical peer-review process. It is only reviewed for overall soundness of experiments (though there are some bad omissions of controls in this case), not for impact to the field, a compelling story, or even believable results. And this is not meant to be a negative comment by any means, but PLOS ONE is a great place to publish potentially interesting negative results, so that people don't keep trying things that don't work.

Anyway, if this was as big as he has trumped it up to be, it wouldn't be in PLOS One, there would be more than one pub, and both the defense department and pharmaceutical companies would be falling over themselves to get this tech developed for humans.

It's this kind of false-hope hype ( I CAN CURE EVERYTHING BUT NO ONE WILL GIVE ME MONEY ) makes people sour on science.