I think Metzen said it was, save for a few details (i.e. Tal'Darin's age).
The events appear to have been acknowledged in Braxis' planet description as well:Following the Brood War, a joint force of renegade zerg and terrans briefly took control of Braxis before the planet was incinerated from orbit by the protoss.
One thing to consider about Kerrigan is that she isn't a regular Infested Terran; even though her personality has been radically altered by the Overmind's brainwashing, she's not a brain-damaged drone like all the others. It thus makes sense that Kerrigan could be desinfested using Xel'Naga technology.
After all, Duran pulled that off with himself; I strongly doubt he was merely faking infestation.
Well we don't know enough about Duran. Most likely you're right and he was never infested at all.