No, he means, if you are going to criticize something, use constructive criticism. i.e. Don't just say, your product sucks.
"Your home page sucks"
Criticism, not useful.
"You should have a better call to action on your home page. I have no idea what I'm supposed to do here."
Constructive criticism, very useful. It tells someone what's wrong so that it can be fixed. If they're very nice, they'll add a suggestion too.
It's foolish to ignore someone's advice just because they're criticizing your project. Often times, if they're criticizing civilly, it's because they want the project to succeed. If you brush them off as "haters", you're just doing yourself a disservice. Honestly examine all criticism you receive. Yes, plenty of it will be useless criticism from people who want to bring you down, but if you don't pay attention to the ones that care, you're throwing away valuable advice and only hurting yourself.
"I'm usually quite pleased with what comes out of YC. That said, in this competitive market, I don't think that being nice (just because) helps anyone the week after launch.
I personally look forward to the day HN tears apart my project so I can say I truly learned something."