When you have reached your 'weekly reward' the fare deducted is discounted to zero when you touch on.
Effectively there is no fine for not touching off, as while the correct fare will not be 'deducted' and the $8.10 default fare will be recorded, since it was discounted to $0 at touch on, there is no financial penalty to you.
HOWEVER if you go to make a subsequent trip and try to touch on at a pole, it will record that as a touch off, and you will end up travelling with out a touch on, which if you get checked by an RPO, presumably is a travelling with out a ticket fine as you your Opal isn't a valid ticket unless it's touched in.
Which makes zero sense, as you can not assume intention to evade fair as the system allows you tap off and pay. How do you prove someone had no intention to tap off if they failed to tap on?