The problem (as it always is with humans) is defining an ideal world.
I’ll repeat a specific line from the section I just quoted, with my emphasis:
Would it be “bad” for them? According to who?
Because this is perhaps the place where it gets most abstract. Who is deciding the ideal?
Because, in general (not putting words in any posters mouth) humans are by default considered social animals. And we put a value on it. But that’s the result of countless accidents of physical and social evolution for one single species. And it’s by no means universal in that. The American (USA) subculture puts a huge value on individuality (often to toxicity, but that’s another thread) or rebelling against the norm. What is that “ideal” society?
Or if we had gone an entirely different evolutionary path, or if some creature achieved sentience but without or specific path of tribalism, would it still be ideal? So again, who chooses?!
So yeah, assumptions must be baked into the debate from the first post. As for the sidebar on choosing to be alone vs. some sort of pathology, I think it’s yet another correlation vs. causation assumption - some people isolate themselves because of an existing pathology, which may be harmful by the majority. Others are just on a different side of the curve, where they don’t value a great deal of human interaction, but that is apparently considered “wrong” despite them doing no harm to others, unless depriving society of their insights/knowledge/money/etc. is decided by the majority to be harm.
My read is that if we were going to have an ideal society by the norms of the majority, then that majority would have had, at some point in its past actively or passively purged all dissenting elements. If the ideal was built around a unified cooperative social structure, then yes, by that societies ideal then those that chose to be socially isolated would have to be forced to conform, or, their isolation taken to an extreme (death, no right to breed, isolate to some form of Coventry, etc.) or they’d serve as a detrimental example to the rest of the human society.
A sufficiently creative society could possibly keep them around but as a negative example, especially if they didn’t get the same support as the rest of the community: “See how bad it is for those freaks?” sort of thing.
But back to my first point, an ideal/utopian world for any number of people is going to be a living hell/dystopia for others. At least for humans, and since we’re the only social and sentient species we can extrapolate from, that’s the way it tends to be.
For me, I could totally see an ideal world of evolved, sentient sessile beings that reproduce asexually and never interact. Perhaps immortal individual philosopher kings, not burdened by the need to act contrary to their own desires. Their Ideal world would therefore be one of perfect isolation! And those that did try to communicate and create a culture would be the ones that needed purging.