That was all resolved in Triumph and Torment as mentioned above in the conversation with Albert1891. You should read it sometime Brubaker's Books of Doom stops short of that era. * Old spoiler * and we find out at the end that the reporter has been interviewing a Doombot. So one can surmise that Doom didn't grant that Doombot the knowledge of what happened when he confronted Mephisto with Dr. Strange's help.
We had an interesting discussion here in one of the older threads about which Doombot that was that Doom has locked away. This Doombot may have been shut away and never given knowledge of the battle down in Hell. Boris tells the reporter that this Doombot ruled for a while while Doom was "otherwise engaged". Doom keeps it around because it is so much like him he couldn't bring himself to destroy it. I thought it might be the Doombot that was in Walt Simonson's FF #350. This was that strange period of time when Doom was not ruling Latveria and Kristoff had been mindwiped so that he thought he was Doom. The real Doom returns and says he's been gone for a while in Simonsons story and he straightens out the mess between Kristoff and the Doombot. He does destroy it's body but keeps it's head. By speaking the codeword Ouroboros, he restores Kristoff so that he no longer believes he is Doom.