yes interesting! as I can see 身 often represents kaya. So does your quote refer to the later fully-developed dharmakāya? I’m not familiar at all with Mahayana literature, in Pali dhammakāya only appears in DN 4 (except for other two instances in the KN):
this designates the Tathagata: “The Body of Dhamma”, that is, “The Body of Brahma”, or “Become Dhamma”, that is, “Become Brahma”
Tathāgatassa hetaṃ, vāseṭṭha, adhivacanaṃ ‘dhammakāyo’ itipi, ‘brahmakāyo’ itipi, ‘dhammabhūto’ itipi, ‘brahmabhūto’ itipi.
Identifying the Tathagata with dhammakāya or brahmakāya is surely not ‘classic’ theravada material 