That said: why did you need a threadpool of daemon threads?
That's a very good question. One of my comaintainers thinks the answer is, "My codebase is old enough to vote and to answer your question I'd probably have to turn our SVN server back on. Please don't make me." :-)
I think the real reason is that the third-party library that we're calling from the threads sometimes takes a really long time to return, which means that unless we use daemon threads the only timely way to shut down / restart the service is kill -9, which is not ideal.