Well, this retort is off the mark. Yes, it's true that vegans do often take a moral stance and advocate for the ethical treatment of animals and the environment. But this is precisely what Nikhil was saying in his original essay - that veganism can be seen as a selfish thing, with one's personal preference being the primary benefit. However, Nikhil also expresses how veganism can be seen as so much more than that. It can be a form of multi-level marketing, where one person's decision to pursue veganism can become a catalyst for change in others. In this way, veganism does have an inherently selfish aspect to it - but it doesn't make the cause any less noble.
At the end of the day, veganism is still about making a positive impact on the world - whether that be through turning others onto the lifestyle, or simply leading by example. And even if it is just a personal preference, it still has an impact on the environment and animal welfare - after all, one person can make a difference. UrRong if you believe that it's wrong to spread the vegan gospel - it's actually a wonderful way to save the world...one delicious plant-based meal at a time!