She is a former FTC Chair so she knows what she's talking about, although her approach to enforcement was more expansive than others. The FTC would investigate, likely along the lines she summarizes, build a case in writing, and refer it to the Justice Dept, which would actually prosecute the case. Not going to happen under this administration, but Khan is saying it's entirely possible that such an enforcement action could be brought to bear, now or later. Personally I hope she gets her job back at some point and does it herself.
I would point out that someone having been FTC Chair does not inherently mean that they know what they are talking about, as demonstrated by the current FTC Chair.
I certainly wish for this to be a productive line of attack against the AI labs, but I'd like to read a more thorough argument showing that it would hold up in court. (It's academic anyway; we'll all be paperclip'd by the time there's a change in administration and a prosecution can be brought and worked through appeals.)