It is absolutely true that some pure vegetarians consider anything that has been in contact with meat to be "impure", though the extent to which they insist upon this varies. Eg if the cook has handled meat, the pure vegetarian might insist the cook washes their hands thoroughly before preparing the vegetarian's food. I've seen pure vegetarians in Subway restaurants ask the cook to change their gloves before making their sandwich.
But it's wrong to assume that by default every pure vegetarian extends this concept of "impure" to the non-vegetarian person, let alone discriminates against non-vegetarians. I don't doubt that some people do it, but it is by no means universal. To ascribe this ulterior motive to every Indian that asks another Indian about their vegetarianism is just silly. It's just a conversation-starter, an ice-breaker, because pure-vegetarianism is so common in India in the first place. And is useful when choosing restaurants for group lunches.
Especially if we're talking about Indians living in the US, treating non-vegetarians like untouchables is going to be a very hard task for them, unless they don't interact with anyone who isn't Indian either. Is it possible? Sure. Is it the norm? Absolutely not.