IMO, introversion (and extroversion) is more than just defining picky people. It’s a personality trait. At least for introverts, it’ll be unfair to “judge” them based on their participation in the conversation, like you’ve tried to do by stating a scenario. Introversion is a preference for environments that are not overstimulating and at least in my experience introverts can’t “pick” things to contribute.
But I can try and help you identify if Suresh is an introvert:
- It doesn’t matter if he’s contributing in the conversation, but at the end if he feels the mere participation has exhausted him, he’s an introvert.
- If he’s horrified by small talks, but looks forward to a deep conversation, he could be an introvert.
- If he thinks he should spend the free time the way he likes — at home, in pajamas— not the way others think he’s supposed to, he could be an introvert.
- If he notices subtleties that others tend to miss, he could be an introvert.
Instead, defining extroverts and introverts as being picky, you can try putting them in the right lighting—extroverts in the Broadway spotlight and introverts in the lamplit desks. Alone preferably. [Ref]