The D7000 manual says the same thing. There's nothing like putting a flash on a camera and trying - which I just did. I mounted an SB800 on my D7000 and took a few shots of a small plant. I took shots without flash, and with TTL BL and TTL. It wasn't a very controlled series, but with flash, the camera chose lower ISO settings than it did without it. TTL and TTL BL ISOs were closer to each other, but since these were handheld shots and my framing varied slightly from shot to shot, I can't draw any conclusions other than the camera must have appropriately adjusted ISO along with everything else, since every shot was properly exposed as I adjusted the shutter speed from 1/250 to 1/3200.