Sri Vaishnava scholar Yamunacharya in Agama Pramanya has stated:
Every man has some Vedic rites for which he is not qualified: the Brahmin is not qualified for the royal consecration, the Kshatriya for the ritual drinking of soma.
If above is true then how come Drona decided to become ruler of half the Panchala kingdom? After Pandavas defeated Drupada in battle and took him as prisoner to Drona, Drona said
'O king, I again solicit thy friendship; and because none who is not a king deserveth to be the friend of a king, therefore, O Yajnasena, I am resolved to divide thy kingdom amongst ourselves. While thou art the king of the country to the south of Bhagirathi (Ganga), I will rule the country to the north.'
If what Yamunacharya said is true, then Drona could not crown himself as ruler. So how does one reconcile Yamunacharya's statement with Drona crowning himself as king ?