The main rationale for wanting it faster for Year 12s is because the education risk from home learning vs face-to-face learning is far greater than any other year. Given the current state of low community transmission in general, the difference in health risk across the age groups in schools is perhaps less significant. Hence, the education risk should be a larger consideration.
I’m not sure I quite follow the rationale that not having to shut schools again come a second wave is a reason to keep them closed for longer. It’s far too conservative in my opinion and even then you cannot predict when (or if) a second wave will come. It may even come when term 3 begins, at peak flu season.
In the current environment, the longer you close schools the more you trade off the educational benefit (of a classroom) for a very marginal health benefit. Having classroom learning as the baseline but preparing a good back up plan for online learning, in case a second wave hits, seems appropriate for the risk in this situation. I just think it’s far too risk averse to definitively trade off the quality of education with what is effectively a small probability gamble on a second wave of infections.
I think the ideal would be to have an ongoing hybrid face-to-face and online learning model on alternating weeks or something like that (for high school students). Unfortunately, that is just not practical because the current infrastructure was never set up for that.
As you noted, the differing approaches probably does depend on the degree of risk acceptance and the individuals assessment of the probability of further waves of infection.
Currently, we are seeing the easing of restrictions without having eliminated the virus. My position is that this is highly likely (>80%) to result in a resurgence of the virus, coupled by dropping temperatures with the coming winter, and that such a resurgence is likely to occur 2-4 weeks after the restrictions are significantly relaxed (probably May 11). This would put the start of the second wave around June, i.e the later part of term 2. Further to this point, if such resurgence occurs, school will be forced to reclose end of term 2, term 3 and 4. If the governments are persistent, they can probably hold out closing schools till term 3 but by then it will be extremely difficult to justify in the case of a second wave.
Overall, the current governments strategy would return to school approximately for 3-5 weeks in the case of the second wave. Considering that the return is only one day a week, the benefit is net three to five days whilst creating widespread disruption. Even with a full return to school, the benefit is only 5 weeks whilst accompanied with significant health risks towards the end of that period.