Michael Cohen doesn't buy Bob Gates' analysis that ceding substantial territory to the Afghan Taliban would send a "hugely empowering message" to al Qaeda:

[A] Guardian story from last month ... indicates al Qaeda is down to 200 core operatives. So to be as blunt as possible who really cares if our withdrawal from Afghanistan "empowers al Qaeda"? They are a shell of an organization that is being consistently hounded not just in the FATA, but in Somalia and Indonesia. What's more, their resonance in the Muslim has declined precipitously. They lack the very capacity or ideological influence to turn such a "retreat" into a fundraising and recruitment opportunity....

And when it comes to empowering al Qaeda, while Gates may be correct that leaving Afghanistan will be a boost to the organization so too would the continued presence of US troops in the country - just as the continued presence of US troops in Saudi Arabia and the perception of US meddling in the region gave impetus to al Qaeda in the 1990s.

By Gates's logic, the US is held hostage to the propagandizing of al Qaeda. It makes their "interpretation" of US behavior more important than the behavior itself.

Good points, although the concern, of course, would be that al Qaeda's numbers and strength would grow were it granted a new haven. As the WSJ argues today:

The Biden faction says changes in the region justify a U-turn: An expanded U.S. force would merely be fighting a motley group of insurgents who aren't planning the next 9/11. This is partly true, but the links between the Taliban and al Qaeda are longstanding, particularly in the Pashtun areas of the south. If America pulls back and lets Mullah Omar create a Talibanistan in Helmand and Kandahar, al Qaeda operatives will soon follow.

Unfortunately, it's just impossible to know for sure whether this would really happen. To a large extent, Obama's decision will be about risk tolerance.