Many people accuse vegans of being too pushy on the grounds that veganism is merely a personal choice. They are using that phrase “personal choice” not in the sense that it is a decision we have made of our own accord (as opposed to when you take off your tin foil hat and the government places the decisions there for you), but rather in the sense that it is something which is acceptable for everyone to have their own unique opinion on.
What is it that makes something a personal choice in the latter sense? Some things we can agree clearly aren't personal choices. “I choose not to murder people, but if that's your cup of tea go right ahead.” or “Molesting children isn't for me. It is your own personal decision what you want to do in that arena though.” Clearly these examples are not going to fly. Some other things clearly are personal choices. “I don't buy orange carpet because I think it looks tacky.” I might advise someone against getting orange carpet, and might even pass some negative judgment against their decorating ability, but I would still fully recognize that they ought to be able to choose any color of carpet they like.
Some other things are not as clear. If someone wishes to eat a highly unhealthy diet putting their own health at risk, most of us would agree that is entirely up to them. If we then point out that the rest of society will then be expected to pay in the form of higher taxes and higher insurance rates to cover for this person's exceedingly high medical costs, suddenly their action becomes much less of a personal choice unless they are willing to cover the full cost of their actions themselves.
In the previous example, when the person's actions were only having a personal impact, we viewed it as a personal choice. When the impact extended to have significant implications for others it was no longer a personal choice. However, when the person once again offered to prevent the cost to others it became their personal choice once again. It appears that we judge something as a personal choice if the only individual who will suffer from it is the one who made the choice.
People who are vegan for animal rights reasons are doing so because of the impact our actions have on other animals. The entire animal rights argument is based upon a characteristic which clearly defines it as not being a personal choice. Accordingly it is unproductive to criticize animal rights based veganism as a personal choice without addressing the underlying animal rights message first.