Perhaps we understand the word differently.

To me, it isn't particularly nebulous, it just means, "People who are currently looking for a new job." Which would roughly be composed of people who are currently unemployed, and people who have jobs but are looking for a new one. I suppose the developers in the story I relate would actually be sort of the latter group looking to avoid becoming the former group, but that's perhaps diving a little bit too deeply into the semantics for a conversation that doesn't involve someone playing bongos or a djembe.

I suppose you could expand that to include, "People who are happy with their job, but could be lured away if you offer them enough money." But it's pretty obvious that that's not a useful subcategory of people for the purposes of the company in the story I'm relating.