The only drawback is that he wasn't a nude woman carrying a small child, so couldn't really serve the Warsaw Ghetto as a vision of Asherah like anonymous nude women did at other camps, including Treblinka.It was not a march to the trains, it was an organized, silent protest against banditry. ... They were the first Jewish ranks that went to their death with dignity, giving the barbarians looks full of contempt. ... When the Germans saw Korczak, they asked: "Who is that man?"
- from Ringelblum's Notes from the Warsaw Ghetto
The Warsaw writers saw him go to the train station in Warsaw, not Treblinka. From there, the assumption is he went to Treblinka, based on... what, exactly?
At least it's said Korczak was deported on a day when the Germans were in the ghetto, unlike Wiernik