I think it might. I think the language is specific to Reserves, re-reading through SD's letter.

With a LC Reserve, there are some obligations to be available (which are not as clear as I thought), but the point is that if you're on LC, you're NOT on rest. Before you do the assignment, you need enough rest. That rest isn't retroactively assigned, and needs to be defined.

A Regular pilot that's not flying has no obligations, and is on rest. Such a pilot getting a WS would be doing so voluntarily, during his rest, if I understand correctly.

Edit: I see it was addressed three posts above.