To me it looked like he fell right in the middle of the ruck which did deserve a penalty. It can be a bit of a grey area the 'going off your feet at the ruck' law. I find if players lose their feet & fall AFTER they've dominantly driven an opponent back & out of the ruck area they don't tend to get penalised for that.
Wallabies still having trouble crossing the line. All the potency of a cuckold in attack at the moment.
Wales look infinitely better in attack, but that isn't hard given I think this wallaby team (so far this year) are unquestionably the worst attacking rugby team in the top 10.