This poll was optional, and you could have simply ignored it.
Your action was exactly the type of thing PG's talking about. In the past, the community at large either would have been truthful or simply not responded. Now, a significant portion of the community is responding non-truthfully. Your motivation doesn't matter: whether it was "not believing in the honor system", or "protesting against the poll", or anything else, you still contributed to the pollution of the data.
I thought I made my reasoning clear in my comment on why I chose not to ignore it. I disagree with having polls such as these on HN (as well as asking people about their gender and race).
According to your logic, people should just ignore posts on HN that they disagree with rather than writing comments, the "if you disagree, just leave" approach.
Maybe I overreacted and should have just commented on this poll and and not marked a wrong age bracket. OTOH, I at least commented on my motivation to to do. The motivation of the other $n people (currently 121-1 = 120 under 10) is mostly opaque.
Your action was exactly the type of thing PG's talking about. In the past, the community at large either would have been truthful or simply not responded. Now, a significant portion of the community is responding non-truthfully. Your motivation doesn't matter: whether it was "not believing in the honor system", or "protesting against the poll", or anything else, you still contributed to the pollution of the data.