I think the balked landing was pretty well done. The only slight criticism might be that the aircraft initially drifted to the left of 17R at an airport where contra-circuit ops may have been occurring. However, the drift looked to be corrected well on climb-out. Hard to excuse the infringing aircraft. YMMB is a major training and GA airport and, even putting neglected or forgotten clearances aside, it's hard to fathom how anyone would taxi there without having the eyeballs fixed permanently outside the cockpit. But we've all been distracted at some points in our flying careers and it's great that this turned out well.
A comment is that the ATSB report (referenced earlier) is superficial in the extreme - a trend we are having to live with here is Australia. No mention of whether there were in fact contra-circuit ops, or whether the two aircraft were on different tower frequencies during the circuit and approach. Most likely they were and, while necessary for sane communications at busy GA fields, the frequency separation does reduce one's awareness of aircraft in the opposite circuit.