nice...
possible feature (just from reading your comments, thus without checking the script): let the script check if the contact was already blocked or not. If it was, don't unblock it when you go back to not-busy.
And maybe in addition: have a kind of 'forced' unblocking (can just be an "Unblock Blacklist" menu item), meaning the script will unblock the contacts, even if they were blocked before.
^^ I think both these things should be standard in any script which block contacts in some sort of automatic way. (for example to avoid those ackward moments when suddenly someone is unblocked which you want to keep blocked)
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