Well the actual argument applies to the general truth. As with every rule, there are exceptions. Some are arguing for the general truth and you are arguing the exceptions.
Aside from cultural acceptance, in and out of the American military, there is nothing keeping the individual woman from walking side by side with a man in a combat seek-and-destroy patrol. But the "exceptions" would have to acknowledge that it would be their responsibility to bend towards the logistical make up of an Infantry Battalion and not expect the Infantry Battalion to sacrifice speed and expedience to cater to gender.
When Marine Combat Training (MCT) first started accepting women as the next step training of Marines after Boot Camp, it was discovered after a few classes that training for the men was sacrificed to accomodate for the women's ability to keep up. This was not intentional, but the natural course of things when men start taking on the role of big brother or leaders have to weigh "team." The women couldn't slow the men down, but nor could they be excluded from the training the men got. The result to this day is that female Marines are "forgiven" for not being able to keep up on hikes or other such rigorous activities and applauded for doing their best. Of course, there are the very few who do keep up and this would be the exception you argue for.
So, it's do-able, but very tricky and would involve a lot of waivers and singled out training for the few. Rules, procedures, and doctrines would have to change. And it would have to be gradual. You mentioned earlier about gays in the military. Clinton's mistake with this was that he sought to appease his constituents early by seeking to force gays in the military. The result was the "Don't Ask Don't Tell" Policy, which had a negative impact on gays in uniform because now there was a forced public policy to conduct administrative seperations where once the issue was usually ignored as a secret. Another result was the complete alienation of the Pentagon from the President. And Clinton proved that it is very hard to deal with international issues without the military in your corner. The President that decides to take the gender step must realize that he has to ease it and not force it. Beyond the mental attitude of the members, the military has to be prepared to do it administratively and logistically.