Just fyi, this is incorrect (they didn't state that, they've actually explicitly named unauthorized third party clients that won't get you banned) and the majority of the osrs community uses unauthorized (all third party clients are currently 'unauthorized') third party clients, primarily osbuddy, which alone has over half of the osrs community using it. So...yeah, they wont be banning "any third party client" any time soon.
And a little bit of first-hand experience regarding osrs: I have accounts that I botted as early as the start of 07 to as late as about one year ago (when I stopped) that I botted with SMART for long periods of time and they still haven't be banned so...SMART client use alone resulting in a ban, in my opinion, does not happen.
E: If you're coming back to botting rs and would like any help/tip/etc, you should come hit up the irc (though I'm guessing you're not =p should still come anyways ) Also fixed my post up a bit ^