Thanks again, Biatch.
The intriguing question is: Would there have been a lower risk of collision if ZPJ had just commenced a climb from base as soon as the risk of collision with XGA was perceived, and XGA had just continued its approach? (That's why I provided a scenario in which the equivalent of XGA pressed on, regardless.)
If I'd been XGA I think I would have just called 'going around and tracking parallel 09 to the south' as soon as I realised there was an aircraft on base, set full power and climbed at best rate and tracked slightly to the south of runway 09. In the circumstances as described in the report, I don't see how that would have resulted in any greater risk of collision than what actually happened. ZPJ has me in sight, and knows where I'm going. I have ZPJ in sight and can watch and listen where he decides to go. We both know about the other traffic.
However, as you say this is just Monday morning quarterbacking. Much rather someone else than me in these situations.