Well, that's not something she knows how to deal with. Everyone in the UNSC is long past denial and into either steely resolve or resignation.

"It's not actually the Flood. Just a set piece for my benefit. The Flood is gone and it's all over."

Cortana had been gone too, according to John, and yet here she was.

No.

Though unspoken, it's as flat a denial as Sombra's. If some malevolent entity wants to get to her, this is the smart way to go about it. (And what that says about the Faceless's reach into her psyche makes it seem even more like the Gravemind.)

No. It's just theatrics. If they look hard enough they'll find the seams in the scenery.