Regarding the negative deeds related to eating meat even of the three-fold purity, there is still no difference from that of the killer. As a majority of the previous great beings of Tibet would not even wear clothes and shoes made with leather or skins, and as they avoided riding animals such as horses, there is no need to mention that they also did not eat meat.
By looking at the Tibetan history books and life stories one will clearly be able to see that the majority of the lineage lamas from the eight great practice lineages including the bodhisattva Asanga, Dza Patrul Rinpoche, Zhalye Tsampa Rinpoche (the first Bokar Rinpoche) and other genuine beings in addition to countless other sangha members of mountain hermitages and monasteries, as well as male and female householders did not eat meat.
That said, authentic beings who are able to lead beings from the lower realms, bodhisattvas with whom any connection whatsoever is meaningful, have eaten meat for the benefit of other beings. From the Sutra of the Exalted Nirvana, “Regarding the powerful deeds to tame others, even eating meat is undertaken.”
Mendong Tsampa Rinpoche said,
Some think, ‘if eating meat is a great negative deed, why do many lamas eat it?’ It is not that they crave and eat food under the power of the conflicting emotions. It is said that they eat with self-assured realization in order to lead beings and other exalted purposes.
So when it is said, “Compassionate people eat meat,” one needs to understand that as explained above. Thus, other than engaging in one’s own mediation on loving-kindness and compassion and giving up meat, one should not denigrate a genuine bodhisattva lama whose acts are actually for the benefit of beings. That would be a very serious fault.
In India the siddhas Shawaripa, Tilopa and others engaged in the seemingly incongruous activities of hunting and fishing. Also in Tibet there was Lama Zhang who engaged in warfare. One should keep in mind that when seeing such lama bodhisattvas’ activities it is beyond an ordinary individual’s capacity to fathom them. For a Mahayana practitioner these activities are not something that should be emulated. In particular, for us the principal objects of our meditation on compassion are the animals. We are clearly able to see that they are tormented by the intense suffering of the lower realms. We are able to abandon harming them and are even able to benefit them to some extent; therefore, we should meditate on compassion by means such as viewing them as our mother. As was said by the unequalled Gampopa,
All my mothers of this place, the sick, old and lowly, others take away their freedom and force them to work, beat and kill them. What a pity! Further as it is certain that all beings born as animals have been my mother, seeing their plight how can compassion not arise? Meditate on compassion desiring to free them from suffering.
These days when most people see butchers, hunters, fishermen, meat vendors and the like they say, “what a shame these evil doers.” Yet they themselves buy meat, enjoy it, savor the taste and even offer a little to the three jewels, boasting that they themselves are Dharma practitioners. Fearing that sickness and suffering will afflict them they invite those who appear to be Buddhist practitioners to perform prayers. They come and enact a ritual without the least bit of understanding of karma, cause and effect or emptiness and compassion. Then the patron offers the flesh of old mothers of previous lives to the monks and even overzealously enjoys the meat himself. Acting like this do they not become even a greater object of compassion than the butcher or fisherman? Butchers and fishermen do not know the Dharma. They have not taken refuge and bodhicitta vows and are not aware of karma, cause and effect. They do not have even slightest discernment to realize that like one’s own body, others’ also experience pain and suffering.