This is just as wrong as a the "perceived leader fallacy" the post is trying to debunk. The person you refer to is a "facilitator" or manager. Leader don't always have to "facilitate" or manage. The manager is almost never the true leader. Leaders should bring the vision AND set the direction AND provide the main motivation (if one person doesn't bring all 3, then you have a collective leadership situation, which is probably the most healthy anyway).
In this example, the actual leader is the unseen person that actually identified that bug as "critical" and decided that the software should in under no circumstances be released without that bug fixed!
(or if we want to find a leader here, at this level, it would be whoever came up with the idea of "what to look for in order to fix the bug" - Martha may have had the idea herself, most likely, or she may have fished it from the discussion happening around her and just happened to be the first one lucky to find the bug while following this "fished" strategy)