There is absolutely no link between a person's gender and their preparedness for combat. That preparedness is determined by skill, training, and talent, not by some arbitrary assumptions based on what equipment a person was assigned at birth. Making the standards gender neutral levels the playing field and gives everyone a fair shot without making snap judgments about them.
Women can be just as capable on the battlefield as men. In the end, combat readiness really just boils down to how fit someone is and how skilled they are with their weapon, and that is down to training and drive. Women may get the exact same training as men, but if they have more drive, then they are ultimately going to perform better because they have the more determination. (This is just an example, this is not me saying women have more determination than men).
On the flip side, you could have some women who get the same training as men but don't have the same drive and just don't try as hard as the men and thus ultimately don't perform as well.
When on the battlefield, it comes down to capability under pressure and how people deal with being in that situation. Again, lets say both the women and men have the exact same training, but the women did better. If they don't perform well on the battlefield and can;t handle that pressure, they simply won't perform as well as the men who may not have done as well in training but are more capable of being on the battlefield.
However, if the men did better in training but didn't perform as well on the battlefield we the women because they simply couldn't handle it, they are not going to do as well as the women.
While it is hard to quantify actual performance standards for something like the marines, and moreso as you further specialize in operations. Basically, for any special forces slanted thing, you aren't assessing for performance to a standard, you are assessing for selection. You see who passes the tests with the most flying of colours.
Arbitrarily saying that a person can't due it because of their genitals simply doesn't make sense. I suppose one could make arguments about biological realities, homogeneity of units, cultural practices that haven't shifted yet (tendency of men to protect women comes to mind, right or wrong), and the like, but at the core, if we value equality of opportunity, we should be keeping gender out of it.
I have mixed feelings about allowing women into all jobs in the military and requiring women to register for the draft. In theory, there should be no limits on anyone from doing any job in the military. I would allow one restriction, that is having the ability to physically perform the tasks required by that MOS.
Most of these arguments are not new. When the military was ending segregation after WWII. Many were afraid the result would losing the ability of the military, well, it didn't. The main difference with women is their physical capability.
Yes, gender-neutral standards should determine who is capable of combat. Aptitude for combat cannot be chosen by what gender a person is, but instead it should be made clear by physical and mental limitations. Each person is unique and capable of different thresholds. Gender should not determine this. If a person can pass the standards set before them in training and excel, it should not matter whether they are a male or female, but rather if they can get the job done. Although women have been seen as the weaker sex for centuries, an individual's performance should be the deciding factor. Therefore, gender-neutral standards are the only way to be forthright in determining capability.
If the gender neutral standards are the same rough and vigorous standards that made the Marines the most elite fighting force in the world and the women will be held to those same standards, then Im all for it. But if you lower standards so more women will be able to pass the test then that is absolute slap in the face to the countless men who have come before and held those high standards. If a woman can reach those standards, more power to them but do not lower standards.
The Marines have adopted more gender neutral standards, but this is not an effective way to determine who is the most capable for combat. It can be vigorous and hard, with demanding physical requirements. While women are capable, they should be able to pass the same rigorous tests that were in place for men.