People who receive downvotes can sometimes believe that anyone who is downvoting is doing so because they must support the opposite of what the poster believes. This, in my experience on HN, isn't necessarily (or even often) the case.
Yes, there may be those who sympathize with Manning. However, there are plenty of other reasons one might find a comment worthy of a downvote: Is it substantive? Civil? Productive? Factually correct? On-topic? Charitable? Thoughtful? More likely to promote good, quality discussion rather than adversarial arguments? You may feel strongly about your position and feel that the subject of your comment is not worthy of charitable discourse (and it may very well not be), but the HN community is worthy of charitable discourse, or at least that's goal. Please help make it so, which includes following the guidelines.