jwb

I mean it's not any one thing it's just that you can make general statements about which moral systems or rules will be more or less compelling to most people based on general trends

I believe morality is ultimately subjective and relative so you can justify eating meat just like you can justify child rape or anything else, theoretically, depending on the moral system. The challenge is how compelling of a case can you make for said moral system to the rest of us. That's a subjective question by its very nature.

Since you seem hung up on this though I can modify the question to can you justify eating meat based on the actual moral system you believe in / abide by rather than some hypothetical system you construct to justify it post hoc.