Depression and suicide aren't feelings that you can reason away with friends or cheer in the best of times. To say that he killed himself because of the court case is speculation at best and likely wrong. Aaron wrote candidly about his struggles with depression and thoughts of suicide. I'm sure the court case didn't help with his feelings of unhappiness, loneliness, guilt and crushing anxiety but to say that he killed him self as the easy way out is... ignorant. Depression isn't rational; it is a terrible disease. It whispers in your ear and tells you that compliments are mere mockery. It tells you that your accomplishments are hollow. It poisons relationships with mistrust and isolation.
I understand that it makes one feel frustrated! Why didn't he just hold out a bit longer or realize that he had so many friends and supporters or realize that even if he lost it wasn't the end of the world or ... He probably did but was poisoned by a disease that affected the very essence of his thinking. Even if he rationally knew that he had lots of supporters, he would be clouded with self-doubt about their motivation or what not. Depression can be painfully frustrating because you just want to shake the person and shout and tell them that people are here for them and that they are smart and passionate and accomplished and somehow make them realize that they have it all wrong if they would just listen.
Many other people have managed to express Atwood's point before his mostly superfluous post (e.g., Lessig) in a much more appropriate manner.
Those who are dead don't mind. (One of the things forfeited in death is the right to be offended.)
Atwood's interpretation and, essentially, anger and disappointment is one of the ways that survivors try to come to terms with suicide.
That it might not be a clinically correct interpretation, in any one particular case or even most cases, may not matter. Does it help Atwood? Might this framing help others get on with their lives?
If you think this 'ragequit' analogy will harm the living at risk of suicide, do you have evidence for that view? I think its effect could go either way: such judgmentalism is unlikely to reach the severely suicidally depressed, but might interfere a little with some mild/early suicidal ideations.
I'd like to summarize by saying that criticizing someone else's way of grieving as 'inappropriate' is itself inappropriate. I'd like to say that, but I can't, because that'd be more than a little self-negating. Whipping out our various still-vital impulses for indignation and criticism is another way that we, the living, poke each other forward.
It's callous because it displays a severe lack of empathy and understanding. As someone who has suffered from serious depression and suicidal thought (to the point where I physically harmed myself) I can say that I was disgusted by the notion of suicide being a deliberate, egotistical choice. I'm disappointed in Atwood, and I can't help but think less of him now.
Being callous means showing a lack of empathy toward others, in this case people who are depressed. Not all depressed people are dead.
Atwood's post may very well be self-therapy, but that doesn't immunize him from the social fallout of his post. One could might argue, for instance, that Achilles' effort in the Trojan war was his way of coping with the death of Patroclus, but that hardly condones his war crimes.