I don't think it's a leading question - I think if they get a large enough sample size, it will be a worthwhile survey of the Python community's 2/3 behavior.
Ultimately, you did pro-Python 3 supporters a disservice by not speaking up.
I suspect the survey is probably selection biased towards 3 as it is. In any event, whether respondents considered it a mistake or not, it's a mistake.
Ultimately, you did pro-Python 3 supporters a disservice by not speaking up.