I don't think so.
In fact, assigning a position to people who don't reply is the equivalent of putting words in people's mouths.
With the possible exception of moderators and admin when it's their job to post, no one is obligated to reply to any post online, whether they agree or disagree with it.
Posting is a personal decision. And I just happened to feel that my position in disagreement with your post was something that I wanted to share. In particular, I feel somewhat offended that someone might construe that I agree with a position (including possibly an offensive one) that, for whatever reason, I do not respond to, whether it's because I have something else I'd rather do instead of directly engaging or because I am simply unaware of what's going on in a particular corner of the Internet.
Took the words out of my keyboard.