Sean (another one) spies a tidbit of solid info over on Bungie's Tru7h and Reconciliation site, in the Two Betrayals Legndary Walkthrough:
sean1 (sean1@qwest.net) writes:
...Well, in the [Two Betrayals] walkthrough, it says, and I quote, "We also discover why the Monitor keeps calling you "Reclaimer." Apparently he confuses you with someone who has done this before, and assumes you already knew what the index would do. When Cortana reveals the key vital tidbit of information, you abandon your former allies."
So, it is clear that there was a last outbreak, and that it was contained...
Good eye. But, who is he confusing you with?