Brahmin is brahmin only if he follows as per vedas and kstriya is kstriya if they protect people as in puranas

 "A brahmin who performs the rituals, as described in the Vedas, only is entitled to be called a Dwija. A

brahmin who is not that proficient in the Vedas is called a 'Kshatriya brahmin'. A brahmin engaged in

agricultural activities and business is called a Vaishya-brahmin'. A brahmin who is in the habit of

condemning and criticizing others, is called a 'Shudra-Brahmin'.

"A Kshatriya who looks after the welfare of his subjects is called a king, while the rest of them are known as

simply Kshatriya. A Kshatriya who indulges in business is called a Vaishya Kshatriya. Similarly a Kshatriya who

engages himself in the service of the three superior castes - Brahmin Kshatriya and Vaishya is called a Shudra

Kshatriya.