Independently - I was passed the list as an effort by SoundCloud to increase exposure. No one til this point had thought about posting it on HN. No affiliation with SC and not in the recruiting business.

With a collaborative spreadsheet like this, my assumption is usually that it was set up by the first person in it.

Does it matter?

Yes. If it was set up from outside it has the feel of imposing a job hunting strategy on people without their involvement.

Given the skill summary of each employee I'm guessing this is an insider effort. And kudos to them! This is a great way to turn a sad situation into a springboard for new opportunities. Would love to see it repeated in the future.

Also what would be the benefit to a head hunter in sharing this data?

That's a fair guess. It was more a "maybe some of them want time off without getting above average interview offer spam". Overall I think it's a good thing too.