User blog comment:Western Gen/Speculations for Season 14/@comment-24202917-20151024155042/@comment-27015560-20151025014826

Maybe it could be someone talking in the background before the final battle, in an eternal time freeze, like Epsilon, explaining why those soldiers were there and what led to the meeting. He did send that message to UNSC so he must have probably recorded a voiceover for the backstories of some mercs.