When a Korban Pesach is prepared for people unable to partake of it, it is invalid. The same applies if it is prepared when its meat is not fit for consumption because the whole intention of the Korban Pesach is that it be eaten. However, R Nattan holds that if mistakenly prepared in a situation where its meat cannot ne eaten, the Korban is valid. Technically the difference between people unfit to eat or meat unfit to be eaten is linked to the role of the Tzitz (Cohen Gadol's forehead-plate.) But in this episode we also extrapolate R Nattan's principle to a social meal outside of the area of Kodshim (Temple Service).