We have to do it. Some of us have to do it in different ways. Doing small things where you can is all well and good but literally none of us are making a single impact in capitalism by making different choices about how we're forced to participate in it. Focus on tearing it down together rather than picking apart individual choices because those individual choices still result in participating in capitalism.
It's saying that vegan's accusing non-vegans of being bad leftists in distracting from class consciousness. Vegans being vegans to reduce animal suffering is obviously good, and I don't think that the comment insulated that it wasn't.