This is not an halachic answer, but rather a practical one.
While it is true that there are a lot of Jewish programmers, and specifically Jewish SO users, it is still a relatively low percentage of total SO users.
Moreover, the odds of a specific user answering your question are incredibly small (well, except maybe for this one, but he's not Jewish AFAIK...) - even if you aggregate all the Jewish SO users, you still have a pretty small percentage overall (definitely less than 1 in 60, though I don't know if that would have halachic implications in this case...).
Even for Jewish SO users, you'd additionally have to:
- factor out the religious Jews, who wouldnt be answering on Shabbat (or chag) anyway;
- factor the different timezones - so just because it's Shabbat for you right now soon after you ask the question, there is a wide range in Shabbatness (? Shabbatability? ...) of other non-religious, jewish SO users;
- Factor the fact that SO is a primarily professional site, i.e. most users use it most often during the work week (okay, Friday afternoon in the winter may have overlap...). In fact, the moderators have mentioned that there is a substantial dip in usage over the weekend.
- Even if you consider only the [non-religious, jewish, SO users who access SO on Shabbat] - its likely they wont read your question (unless it's in one of the most popular tags, or *really well written - but what are the odds of that?? ;) )... and even if they do read it, it's an even lower percentage that would answer it right away.
- For that matter, even if you ask your question on Tuesday, there is a practically even chance of it being read and answered by a [non-religious Jewish SO user during Shabbat in his own timezone].
- Also factor the fact that even if you didn't ask the question, that [non-religious Jewish SO user during Shabbat in his own timezone] would likely be answering other questions instead. So you are not causing him to violate the sanctity of Shabbat, that is of his own choosing. (And btw - if SO were to shutdown on Shabbat, he'd be doing something else instead - FB, SMS, driving to pubs or the beach, whatever...).
As for benefit - and I'm not sure this is the exact halachic position - but I was taught that one can benefit from some forms of chilul shabbat, provided that you are not benefiting from the fact that it was chilul.
I.e. if it could have equally been done after shabbat, but happened to have been done on shabbat, then it's a just a question of leaving enough time after the end of Shabbat, such that it could have been done after Shabbat (in order that you dont profit the "preparation" time).
In short, if you happen to know with any level of certainty that a [non-religious Jewish SO user during Shabbat in his own timezone] answered your question - wait till long enough after Shabbat. If you were to know that he would be answering your question and only your question, you'd probably be better off not asking at that point - but then again, there is no reasonable way to know that (unless you really try...)