There's one thing that I think makes this article very unhelpful though. It doesn't matter if your depression is a diagnosable illness or not. What matters is that you want to be helped, and if treatment can help, you should seek it. I use treatment in the broadest possible terms, not meaning a doctor should give you some pills to take.
If you are suffering the grief of a lost one, you want to be helped. That might be talking to a professional, it might need to be with medication if it pushes you over some edge. It might be time as a great healer. When my father died, there definitely came a point when my mother wanted time alone as part of the process.
Unfortunately, this article veers towards the "pull your socks up" school, unless you have one of the particular specific conditions which get the Professorial stamp of approval. I don't think this is what he intends, but it is the impression I got. He is quite right to say that the "diagnose-for-treatment" route is potentially harmful, but I wish he had emphasised very strongly that the right treatment without a diagnosis can be the right route for many.
It's not my main point, but there's a very odd thread running through this. It's the "pain is good for you" vibe. He's not disputing that people in grief suffer greatly, but he does seem to think that the pain being experienced should not be alleviated. As if a doctor said "we've got painkillers but since it's natural to feel pain after you break your leg, we're not going to give them to you."