Day 3 Jivaka Sutta -MN 55-Monastic Retreat with Bhante Saccananda 

How does it matter whether it was killed for oneself or not? The fact remains that it was killed, it underwent suffering in the process of being killed, the being that killed it underwent demerit. If a group of people were to announce that they were looking to buy human meat, and that they would be willing to pay any butcher who provided it, and the butcher goes out and kills humans to supply it, would the group of people who created the demand for it be held blameless? I don't need a precept for it, this is common sense.

In the time of the Buddha, there were no processed food markets, and if you wanted meat, you had to kill it on demand. The Buddha was probably pointing out that if meat already existed, you might as well eat it. There is a ssubtle distinction here between that and creating a mass chain of responsibility shifting so that these "monks" can absolve themsselvess of all the blame by cravenly shifting it to the butchers. In this sense, the butchers can be thought of as the "weapon", in the language of the precept, that the monk usses to kill the animal. But I don't expect these dimwits to undersstand that.