In other words, he was not saying that negative criticism should be dismissed. He was saying that there is too much negativity for him to find the site enjoyable and that he thinks the change in attitude is for the worse.
That said, I also think that you're off the mark when you say the OP is not ready for having a personal project on display. The premise of OP's note is that he considered HN to be a more positive, supportive community than the larger Internet. There is nothing wrong with wanting to associate yourself with people who will build you up rather than tear you down. If Steve's been using HN for five years, he's probably well aware of how vicious people can be on the Internet. It sounds like he's sad that HN isn't a haven from this viciousness like it once was. And just because he's sad that this one community has deteriorated, that doesn't mean he's not capable of handling the slings and arrows of the wider Internet population.
I have noticed in the last year on here it's become a lot more like other sites with more general hacker interested threads and (maybe I'm wrong) less and less startup relevant stuff. I know HN is for both, but I personally come here for startup signal.