Not very re-assuring (for a security plugin) that it is not regularly updated and has support tickets that are not replied to regarding that topic. I understand that this is a free plugin; I’ve seen some other free plugins that don’t get updated often (and indeed don’t need frequent updating) but some of those authors note as much in a sticky forum post to let users know that it still works and is maintained.
If the authors of Spam Zero still keep and eye on this and only update when it is really needed, they could note that in a sticky post on the forum; I’d feel much better if that were the case.