There is that old Latin saying: "Si duo faciunt idem, non est idem", meaning - If two do the same is not the same. So we can't really generalize about such behavior. The only yardstick of "normalcy" would be how much the kid in question is displaying being happy in what they do while secluded into their own world. If they are depressed and need a special attention then they are escaping into loneliness and showing those signs of resentment towards all intruders.
A happy introvert is still showing enough willingness to be around others with a reservation that they may not participate a lot. Unhappy ones will insist on being lonely and show a high level of intolerance, if not animosity towards everyone around.
As for the society and how they may treat a genuine introvert - who really cares what they have to say. At this point it becomes a matter of a personal philosophy dealing with our freedom to be ourselves, and who is called upon to impose limitations to it. Even extroverts become a pathetic picture of social duplicates when they neglect their individuality for the effects of "belonging" to the herd.
We have to be clear whom we consider as our "authorities", whose opinion really matters - before we give up our own as the only one that matters, because ultimately it's our life.
Many people show that tendency to live everyone else's life except their own, and they become very "smart" with advices and warnings, while having their own closets filled with skeletons. So, we should ignore such smart asses, or put them in place, whatever suits our temper. There are no such social "norms" that require everyone to behave the same way. If that would be the case, we might as well emigrate somewhere.