If the person (NOTE: PERSON) can meet the physical standards required then they should be allowed to give it a shot.
That's fine in theory, but as I'm sure you understand implementing that is not so simple. By far the biggest problem I see, is just how and when do you test if people if they can make the grade or not? The PES test might be an excellent test to see if people are able to perform that job, but it can't be used to test new recruits to see if they can hack the job or not.
For example, looking at the army, you pick your corps at recruiting before you get to Kapooka. Does that mean that budding infantry recruits are going to do the infantry PES test before getting on the bus? Of course not. The vast majority of males wouldn't pass the test before training, let alone females. Do you do the infantry PES test at Kapooka? You've been there, and as you know that isn't feasible. We currently struggle to get recruits fit enough to pass the recruit fitness assessment as it is (and that test is less challenging than the current BFA). There is simply no time to train soldiers up to a higher standard.
That means the first place that recruits are realistically going to be screened is at IETs. By then it is too late. What if the recruit fails the assessment? How many times are you going to let them retest before you tell them to pick another corps? Of course, this is a problem with male recruits already, but the problem with female recruits will simply be that much greater. For instance, the failure rate for females on the all-corps PES test is about five times that of males, with more than double the injury rate. Add in the higher standard, and what will the failure rate be then?
What I can guarantee is going to happen, is that large numbers of females, strong women with the best intentions, are going to have to complete remedial PT for weeks/months just to reach the minimum standard. They are then going to have the same problem each and every six months when they have to redo the test. Then they will actually reach a unit, have to go bush, and realise the actual job is so much harder than the test, struggle hard to keep up with the men, and break themselves. I am willing to bet a large sum of money that for the first few years that females are in combat jobs, more than half of them are on long term medical restrictions due to being broken.
That is going to be the reality for units - having to spend an inordinate amount of time on admin, remedial PT and rehabilitation to get recruits up to an unrealistic standard of personal fitness. Now this is a problem with men already, but a small one. The vast majority of men, no matter how unfit when they start, will be able to be brought up to the standard required of combat jobs. The basic truth, supported by lots of medical evidence, is that the vast majority of women will not, and they will pay the price for trying.
That is not a slight in women. I have served with many outstanding women in uniform, including on operations. There are women out there that put men to shame with their fitness. For instance, I remember putting a reserve platoon through Kapooka where the soldier that won the award for best at PT was a 47 year old mother of three, who had a daughter older than I. I was in peak shape, and I had to struggle hard to beat her during the final fitness test (I was hungover/still drunk, but still). However, when you are talking about the thousands upon thousands of soldiers in uniform, these women are few and far between, and the army/ADF is going to pay a high price for letting the remainder try to reach an unrealistic standard.