<<I'll take a wild guess at this: he had a functional cure and will eventually need another dose. The bad guys have multiplied and will eventually increase.>>
I don't think so. The viral fragments would have multiplied by now if they could. IF they are there his immune system is clearly keeping them in check. Brown says re-infection is not a possibility so we should take him at his word. (however, there are strains / mutations of HIV that don't use the CCR5 receptor for infection.) Since the findings are at the far limits of detection, its most likely either a contaminated test / lab.