Logically, President Biden would throw Gen. Milley under the bus, and hang the botched withdrawal from Afghanistan around the general's neck. I've been wondering if the reason he doesn't is because the price of Milley's silence is keeping his job? Here is a Daily Mail (U.K.) article which hints at this scenario.
I suspect Milley told Biden pulling the troops out before getting the civilians out, and doing it during the summer "fighting season" wasn't wise. I further suspect that Biden told him to do it anyway, and Milley obeyed the Commander in Chief, as he is required to do.
If that scenario represents what actually happened, a fired Milley would immediately report what happened and hang the responsibility right back around Biden's neck where it belongs. So he keeps his silence, thus his job, and the responsibility remains diffuse and unclear.
If that is what happened (I have zero insider knowledge of their actual interaction), an honorable man would have resigned and told the truth. An ambitious guy who spent his whole career playing organizational politics, aiming for the top and doing whatever it took to get there, would do what Milley has done.
Note: About the Afghan "fighting season," Kabul is at 5876 ft. elevation. That is within a couple hundred feet of the elevation of my part of Wyoming. I promise you winters at this elevation are long, cold, and snowy.
Specially trained and equipped mountain troops can fight under these conditions, but it is brutally hard, in spite of what a couple of Bond movies showing fighting on skis have hinted. The Taliban wisely choose not to do it.