It's true that the discussed statistics do not rule out an interpretation like the new leaders add to longevity by steering the organization into tamer less effective strategies, as opposed to my own favored implied interpretation, that 'old leaders stay too long and drag down organizational performance & survival'.

But you could probably cross-check her list of organizations with assassinated heads, and compare against Max Abrahms' list of the 7% successful terrorist organizations and see whether survival correlates with success. (I'd bet it does.)