jefesse:
Some authors are probably not around anymore to provide permission. For instance, I'm reasonably certain that "Carolina Jim" passed away some years ago.
In theory, at least, his heir or heirs, whoever they might be, have the right to authorize or forbid publication. Copyright extends well beyond death. Seventy years beyond in most countries for recent works, although it varies by country and US laws in particular are rather complex depending on the date of creation and publication.
I, for one, approve of the LSF's stated policy of not posting work without a clear grant of permission from the author or authorized person. Yes it does mean some good work will be lost, and that is a shame. But it also means that authors can trust that they ahve control over their own work. It also means there is no chance of anyone suing the LSF staff cor copyright infringement.