That site also has a 2019 interview with John Barnett. The site is named and the interview is quoted in today's Daily Mail article on the whistleblower's suspicious death.
So, corporate crime reporter appears legit; the whistleblower spoke with them in 2019, and his lawyer did write to them with details.
Threads is actually #7 on this ranking: https://fed.dembased.xyz/weighted
Meaning it is widely defederated, including by instances that have shorter block lists.
Anyway, that whole list is ugly.