Ahrar al Sham is a pretty large, strong Islamist group that has had considerable success against the Syrian régime lately. It isn't linked, verbally or substantively, with Al Qaeda. It is supported by Turkey and Saudi Arabia. It got a lot of attention in the West lately because its "head of foreign political relations" wrote an op-ed in the Washington Post suggesting that, long story short, Ahrar is nice. However it is anything but a secret that Ahrar is not that nice, and on good terms with Jabhat al Nusra to boot. Jabhat al Nusra is linked to Al Qaeda.
Together these groups are a major force against both IS and Assad. The US will never back either group, but that's exactly why Turkey and Saudi Arabia are Syrians' only hope of ending régime slaughter. The US offers at most covert and minimal support for anti-Assad rebels, because it doesn't trust such groups to keep away from well, Ahrar and Jabhat al Nusra. Its own officially 'trained and equipped' 'rebels' aren't even supposed to fight Assad.
Sam Heller and Aaron Stein seem concerned that the US might be failing to prevent Turkey and Saudi Arabia from supporting Ahrar al Sham. They say that any support for Ahrar Al Sham is "runs counter to US interests"
Just what might those interests be?
Not oil, the US is awash in oil. Not defense of its bases in the Gulf States or Turkey; no one is going to dislodge the US from there. Given the permanent massive US presence in the area, the Gulf States have nothing to fear from Iran. Nor can Israel be a US concern, because Israel is more than capable of taking care of itself. Any Islamist threat in Egypt will not be made better or worse because some arms go to an Islamist faction opposed to IS in Syria. Ahrar al Sham can't pose a threat to American interests because America's now minimal interests in the region are short term and mainly involve its impregnable defense installations. The only conceivable concern that might be affected is some possible growth of Russian influence in the area. Since Ahrar fights the Russian/Iranian client Assad, that interest is, to a tiny extent, served by any support it gets.
If US policy in the area is a disaster for the area, that doesn't matter to the Americans. What they care about is that the policy, a bunch of gestures, be cheap in both dollars and US lives. Weapons going to Ahrar al Sham would not run contrary to that objective.
What appears to be behind Heller and Stein's odd claim is that Ahrar, contrary to any impression it might try to give, doesn't Share Our Values. Those, one supposes, are Freedom and Democracy. But past history aside, it's clear from US support for Sisi that these values aren't dear to 'our' hearts. Even if they were, there is no course of action the US is willing to take that would advance them: that would take massive troop commitments, a 'nation-building' exercise. Given that the US has proven itself incompetent at such exercises, the whole idea of furthering Our Values in the Middle East must be counted a non-starter.
And even warning the US about Ahrar is a puzzling motive for the article - do the authors think that Americans somehow don't worry enough about Islamists? If Heller and Stein want to stress that they don't like Ahrar and don't enjoy seeing them get any support, why not just say so? Why pretend there is some political rationale for this expression of sentiment?
Heller and Stein's post raises a larger issue, the manner in which Western powers perceive their role in Middle East politics. It is a mistake to suppose that if you back someone in, for instance, Syria, you have no influence on them. No doubt Ahrar, should it acquire some power in Syria, would 'out of the box' do little to improve the situation. But if it were to acquire some power, it would only be because of its outside support. Outside supporters would therefore be in a position to affect how Ahrar conducts itself. It therefore makes no sense to give advice as though Ahrar in power would conduct itself according to its present agenda. The West might be more willing to end the horror in Syria if it allowed itself to realize that it could, after all, do much to shape the aftermath.