That was my initial reading, but Krewenchuk was their bomb aimer, not rear gunner (unless something had happened to their rear gunner before being shot down.
I believe the ID documents were Krewenchuk, in addition to the rear gunner having been pulled out from the turret.
But I don't read German fluently, and the author of the text certainly centred on Krewenchuk.
I read it as him describing two incidents, the rear gunner in his turret and then seeing ID docs of the bomb aimer, as I wouldn't ordinarily expect him to be in the rear turret when they were in the vicinity of the target, where he'd have been needed to release their bomb load.
But I bow to your better understanding of the article.