I think something is lost in the translation : ทุกอย่างเป็นอนัตตา (รวมถึงนิพพาน)

If we read the tipitaka enough times, we would see that "ALL CONDITIONED THINGS" (But Nibbaana is NOT conditioned) are 'anatta'.

Conditioned things are things that rise and fall away -- 'nicca' hence lead to 'dukkha'.