Can we not? Do you think that they would have wanted the thread about their death to be filled with speculation about whether he killed himself or drank himself to death? No one knows anything, and even if they did it would be impolite to offer up that information.
I think if he did have mental health problems, like many others in the field, it's now more than ever to raise the point. If he didn't it doesn't hurt to raise the issue, because it is genuine.
If you suffer from anxiety and/or depression, there is help. Talk to someone. You're not alone, and you don't need to suffer alone.
He was a great mathematician. But I'm still interested in how he died. So actually, can we? You're free not to participate in that which you find distasteful, but we're adults here.
He was a great mathematician. RIP.