Mariupol is in the DPR, Those two aren’t just the capital cities, but the entire former oblasts. Kherson and Zaporozhye are separate oblasts yes, but both them two and the LPR and DPR will be holding referenda on joining the RF, and since the Ukraine does not recognise the (factual) independence of the LPR and DPR, it makes sense that they would consider LDNR citizens voting to join the RF in this legislation.