
That version fixes everything!
And I figured out the multiple users thing...I was doing what was intuitive and putting a space after the semi-colon like a list...but no space can go there. So I'm altering the template to put a warning about that for my users (who aren't the most computer literate sometimes!).
The only problem that's keeping me from making this live now...when the thread shows in the Last Post column and you click on it, you can see it no matter if you're supposed to or not. It's like that call doesn't check the private_thread_not_allowed().