IRule causes Virtual Servers to be "up"?

I believe that the virtual will inherit any monitoring state of a pool referenced in an iRule. Your previous rule didn't contain a pool - thus it had no monitoring associated with it. Your new rule references 2 pools. It would only take 1 pool member among both pools to make the virtual "up". You can test this by marking all pools down and looking at the corresponding virtual status. I seem to also remember that if there are no monitors on the pools referenced within the irule - then the virtual where that irule applied with always be up. I'd personally love some confirmation on that, but that is at least the behavior that I've observed.