Islamic State-linked women arrested in Australia on return from Syria

I'm not assuming anything, but it has been pretty widely reported that these women likely don't have access to any other valid citizenship. Australia has mechanisms to strip dual citizens of their citizenship in absentia if they've engaged in terrorist acts overseas, so if Australia had sufficient proof, it would have happened already. This has also been one of the more controversial aspects about Australia refusing to aid in their travel back to Australia because it's illegal under international law for international airlines to allow on passengers who don't have any travel documents, and none of them had passports. So with Australia refusing to communicate with the Syrian government and the women having no other known citizenship, these women had no way of getting travel documents, and were thus functionally stranded in a country that wanted to get rid of them.