These are just my own thoughts — I would love to know your thoughts as well. — —
For me, I believe it boils down to the teaching of ’skillful means’ as well as ‘intention’.
Intention: If you kill an animal just to eat it, or, if it is killed specifically for your meal, I feel it to go somewhat against the 1st Precept of No Killing. I have vowed to try and live by the 5 Precepts.
Skillful means: This is where it would be permissible, according to my view of the Dharma. But, it is also where one must ask themselves what their own life dictates.
Example: A monastic that sustains their life from alms, would likely do so by using what is offered. Sometimes meat would be offered. Also, monastics that live in certain areas of the world would have a harder time sustaining a vegetarian lifestyle. Just a reality of this world.
I happen to live in Southern California — it is quite simple and accessible to live a vegetarian lifestyle. Therefore, my skillful means allow me to be a vegetarian. However, when I travel, I do find it difficult in some areas. (When I traveled to New Orleans again years ago after becoming a vegetarian, we’ll just say I ate a lot of bread, salad, and cheese pizza. hahaha) I have also taken Bodhisattva vows for this lifetime. In doing so, I find it important for my path to work as hard as possible to keep a compassionate mind. I cannot do so by sustaining my own life from the suffering and killing of other sentient beings. This keeps me being a vegetarian.
Now, having said all that, both my wife and my son do eat meat. This is something I cannot and will not change. It is a decision each individual must make on their own.
The path of Buddhism does not prosper by forcing others into one’s own way of thinking, but rather through living a life of compassion and helping others either through actions or examples.