I assume you saw the same thread I just did. Or maybe it was a different thread regarding another comment about search. I didn't read it as negative (although it very well could easily be interpreted that way). I guess interpretation is in the eye of the beholder. I personally try not to read or react too much to stuff written online. You can't hear the expression behind the words sometimes and things can easily get misinterpreted. That isn't to say HN doesn't have its fair share of negativity.
In regards to the thread I just saw, I looked at it as a valid question in reply to the response comment above it. I didn't see it as a negative reaction. In all honesty, it was a valid comment (disclaimer: I've never used either of the services the debate was regarding so I can't tell whether or not search was lacking and this isn't a reply about that). Regardless of what the product is or whether or not we're talking about the same thread, if someone suggests something, and someone else feels there is an inefficiency (perhaps base on how they use it), those comments may not be valid for some readers but they are valid for others.
For example, I use Yelp more times than I can count. I think its a good service and solves a need on some level. But even I have to admit the search function on Yelp is beyond stupid. There are times when I've done a search for something like Chinese Restaurant and will gets result for things like an American Yogurt Shop or a Grocery Store. If someone else is trying to build say a Yelp competitor and posts a thread on here about it, and another person comments about Yelp being a competitor and links to them, I don't think its invalid that I bring my frustration about Yelp's search problem. Both can be helpful in their own way. It's just a matter of how you choose to perceive the comments.
Or in the case of your specific example, perhaps it was worded rudely but you can try to perceive it as a way of giving feedback. I personally try not to take offense on small things like that. It's not really good for your health.