Instead, they're correctly observing that there's a correlation between scientific bona fides and scientifically accurate speakers. And that organizers will be better off if they use that as one rule of thumb in evaluating speakers, which is also true.
You only see an argument from authority because you've reduced their argument to a straw man. The purpose of TEDx isn't to be a final arbiter of all things true; it's just to surface things that are true and interesting.
They're popularizers, not the cutting edge.
You prefer non-authoritative information?
From your link:
>Although certain classes of argument from authority can constitute strong inductive arguments, the appeal to authority is often applied fallaciously: either the authority is not a subject-matter expert, or there is no consensus among experts in the subject matter, or both