Yea they made a mistake not verifying signatures from the beginning. But they have course-corrected, see this notice FLI has posted now above the signatories list:
Due to high demand we are still collecting signatures but pausing their appearance on the letter so that our vetting processes can catch up. Note also that the signatures near the top of the list are all independently and directly verified.
Yea they made a mistake not verifying signatures from the beginning. But they have course-corrected, see this notice FLI has posted now above the signatories list:
Screenshot