Is a settlement agreement valid if men in a besieged fort offer Jizya only for the women and children, exempting themselves?

Primary text

If men are present in the fort with the women and they request a settlement where the Jizya is imposed only upon the women and children, excluding the men, the settlement is invalid. This is because they designated the obligation upon those upon whom it is not incumbent, thereby absolving themselves from that which is obligatory upon them.