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).