Q: Lord krishna advises Arjuna that Anatma alone is killed. Can meat eaters extend the argument to their killing for food?
A: Matter is anAtma and is inert. It depends for its existence on Brahman.
All life forms manifest Consciousness to some degree. Man is unique in having an intellect that ‘reflects’ Consciousness, enabling self-awareness.
Everything is brahman, being just name and form. Nothing is ever born in reality. Nothing can be ‘killed’ in the sense of destroying Consciousness, which is eternal and unchanging. It is only anAtma that can change its form but it cannot be destroyed either (c.f. conservation of mass-energy).
Within the context of that understanding, therefore, it is a question of ethics, custom, upbringing and so on that dictates one’s attitude to the ‘right to life’ of the various species. Man has to eat to maintain the body and everything that is eaten for that purpose either is or has been alive.
The topic of ahiMsA is key to Jain and Buddhist philosophies. It is not a particular issue in Advaita. Its mention in the Gita is probably rather due to its significance for Yoga philosophy.