"Indeed, there are several Vinaya rules that were laid down in response to the actions of arahants. An arahant cannot act in an intentionally harmful manner, so these rules cannot be taken to imply that the motivation behind the acts was wrong. The acts have unintended harmful consequences, and this is why they are prohibited."
"The notion that actions should not be done, even when they involve no harmful intention, is found constantly in the Vinaya. For example, a monk is criticised for baking bricks that have small creatures in them, even though he was unaware of them and did not intend any harm. The Buddha laid down a rule forbidding this."
To frame the debate around the consumption of meat in purely kammic terms is to, in my mind, miss the point. An action that leads to the suffering of living beings should be avoided (as per the Buddha's instructions to Rahula) regardless of whether or not the intention behind it is pure; as quoted above, many Vinaya rules address behaviors that were performed without even the possibility of malice or ill-will. If it is truly intention and only intention that matters in regards to the worth of an action, then why did the Buddha stop the monk from killing creatures he did not know existed? If intention is the sole determiner of an action's moral worth, then why did the Buddha prohibit an action that, while destructive, had no intentional harm behind it?
I believe a far more realistic approach to morality would dictate that we, as Buddhists, should not only cleanse ourselves of any malice or ill-will but also attempt to investigate our habitual behaviors and see if they fit the rubric provided by the Lord Buddha to Rahula:
I don't think that a Western Buddhist, having available to him or her mountains of data illustrating the affliction that the meat industry brings upon living beings, can honestly look at their purchasing power and see it as completely devoid of complicity. The question is not what we can get away with, or what the precepts do and don't allow, but what does or doesn't lead to suffering; I would at least humbly suggest that those who consume meat really examine the nature of the industry and see if they come to the same conclusions.
"Whenever you want to do a bodily action, you should reflect on it: 'This bodily action I want to do — would it lead to self-affliction, to the affliction of others, or to both? Would it be an unskillful bodily action, with painful consequences, painful results?' If, on reflection, you know that it would lead to self-affliction, to the affliction of others, or to both; it would be an unskillful bodily action with painful consequences, painful results, then any bodily action of that sort is absolutely unfit for you to do. But if on reflection you know that it would not cause affliction... it would be a skillful bodily action with pleasant consequences, pleasant results, then any bodily action of that sort is fit for you to do.