The women, who are shouldering the same packs and wearing the same combat uniforms as the men, are barely distinguishable from the men as they trudge in the darkness.From this (linked) USA Today article.
"We treat everyone the same," said Staff Sgt. Billy Shinault, a Marine instructor who chatted while working a bolt of chewing tobacco after the hike. "We would be doing them a disservice to lower the standards."
In combat, gender really doesn't matter. The only thing that matters is the answer to the question, "Can you carry the gear and do the job?"
When it comes to infantry of any sort, if the answer is "no" then standards should not be lowered. That person should not endanger the rest of the unit by insisting on participating. If the answer is "yes" then it really doesn't matter what person's gender is. They can do the job, so they're in.
Note that they routinely carry 85 pound packs, and sometimes carry extra temporary loads, like ammunition or mortar rounds for other units. Not all men can do that. Not all women can do that. The Marines are smart. They're accepting anybody who can do it and wants to do it.