People often have a vested interest to lie about themselves, and often people may not remember historical details about their lives as accurately as they believe they do.

That said, "no really, I am still alive" seems like something that should be trusted as a source.

> Self-published or questionable sources may be used as sources of information about themselves

Clifford Stoll's own Facebook page saying he's not dead can be cited on Wikipedia, even if Facebook itself (or Clifford's non-expert opinions) are unreliable