Потому что иначе невозможно пометить эти слова, которые в оригинале написаны по-русски. Жаргон, используемый в книге (Надсат - от "-надцать"), основан на русских словах:
There was me, that is Alex, and my three droogs, that is Pete, Georgie, and Dim. Dim being really dim, and we sat in the Korova Milkbar making up our rassoodocks what to do with the evening, a flip dark chill winter bastard though dry. The Korova Milkbar was a milk-plus mesto, and you may, O my brothers, have forgotten what these mestos were like, things changing so skorry these days and everybody very quick to forget, newspapers not being read much neither.