If they are making false claims about you that cause serious damage to your reputation (like telling the FBI you look like a terrorist), then sue them for libel.
Wouldn't you have to prove you don't look like a terrorist?
Clearview is probably saying that if you convert an image, or set of images, of a person to vector(s) then there are some similar vectors that are associated with a terrorist. If they are saying it, it's because it's probably true in their implementation.
I probably do look like a terrorist somewhere. The problem isn't identifying that person and associating them with me, the problem is treating that information as significant, and that's on the FBI (in your hypothetical scenario).
Clearview is probably saying that if you convert an image, or set of images, of a person to vector(s) then there are some similar vectors that are associated with a terrorist. If they are saying it, it's because it's probably true in their implementation.