Allowing only active connections when member is disabled

Well, as far as setting node states, that's something that's better handled by iControl. Click here

If you're just looking to use the same rule and have the VIP not respond if all nodes are down...try using discard instead of reject.

when CLIENT_ACCEPTED {
  if { ([IP::client_addr] eq "10.10.192.8") || ([IP::client_addr] eq "10.20.192.8") } {
    persist none
  }
  if { [active_members stl-ac24-pool] == 0 } {
    discard
  }
}

This should appear as a dead connection, since it will just drop the incoming request if there are no active members.

Hope this helps,

-Colin