How is a yes/no question aggressive? At that point the maintainers had two possible responses:
1. Yes you are missing that ...
2. No that is the complete picture.
But they chose to side channel to a third possibility, "we are put-off by your questioning!". Excuse me what?
Have you stopped beating your wife?
More relevantly, when the question is asked genuinely then - as you say - it's expressing an openness to learn.
Sometimes it is asked rhetorically, dripping with sarcasm and derision. In that case, it is clearly not furthering our interest in productive, good-faith discussions.
Far more often, it falls somewhere between those two and - especially in text - is often ambiguous as to which was intended. While we should exercise charity and hope our conversational partners do likewise, it makes sense to understand when some phrases might be misconstrued and perhaps to edit accordingly.
I would say that incredulity falls within the range between "completely inoffensive" and "outright hostile", and very much toward the former side of the scale. It can be hard to distinguish from feigned incredulity, which (while still far from "sarcastic and derisive") makes its way toward the other side somewhat.
It's all a matter of perception and context, of course. And though you say there's only one way to interpret it, even you describe it as a continuum.
Sadly, this is all just a sad missed opportunity.
MS could have been less defensive and more open to possible solutions. The genius programmer could have slowed his roll a bit and could have been more collaborative.
It's not just "Am I missing something?"
It's:
"Am I missing something? Why is all this stuff with "runs of characters" happening at all? Why would you ever need to separate the background from the foreground for performance reasons? It really seems like most of the code in the parser/renderer part of the terminal is unnecessary and just slows things down. What this code needs to do is extremely simple and it seems like it has been massively overcomplicated."
Perhaps frustrated that they don't really seem to be on the same technical page?
I tend to think these things can go both ways. I feel pointing out someone's frustration in writing tends to make things worse. Personally I would just ignore it in this case.