There are social and intrapersonal reasons to avoid eating meat even if doing so doesn’t lead directly to more animals being slaughtered. It is still treating the dead bodies of animals as a commodity, something we don’t do to the bodies of dead humans. And it will take a cultural shift in how we see animals in order to end their oppression.

And the issue of eating “wasted” (weird way to talk about it as a vegan) meat is more concrete when you are eating meat at a function or the leftovers of a friend. The next function is going to have just as much meat if not more because it all got eaten. Your friend isn’t going to think about reducing their meat consumption because they were left with too much, they might even get more satisfaction from you eating it because of pity. People who regularly consume animal products often think going without them must be suffering.

I don’t agree with freegans, though I also don’t really care what they do. As long as they understand there is a clear distinction between something like dumpster diving and a potluck.