Is one candidate a 'recruiting sergeant for the terrorists'?

Smoke raises behind an Islamic State flag after Iraqi security forces and Shiite fighters took control of Saadiya in Diyala province from Islamist State militants, Nov. 24, 2014. (Photo by Stringer/Reuters)
Smoke raises behind an Islamic State flag after Iraqi security forces and Shiite fighters took control of Saadiya in Diyala province from Islamist State militants, Nov. 24, 2014.
In the 2004 presidential election, the first national race after 9/11, there was considerable focus on national security and the question of which candidate was better prepared to combat al Qaeda. Just a few days before the election, Osama bin Laden released a new video, which only served to intensify the debate.
Though CIA analysts later concluded that the terrorist's message was "clearly designed to assist" then-President George W. Bush's re-election, the video had largely the opposite effect. John Kerry later said the bin Laden tape contributed to his defeat.
Twelve years later, bin Laden is dead and al Qaeda's potency has waned, but a similar political fight is nevertheless underway. The New York Times reported overnight:

With a manhunt still in progress before an arrest later in the day, [Hillary Clinton] sought to shift the terms of the presidential contest back in her direction. She called [Donald Trump] a "recruiting sergeant for the terrorists" and, from a rainy airport in White Plains, offered herself as a seasoned warrior against terrorism. [...]Citing former intelligence and counterterrorism officials who have criticized Mr. Trump's caustic remarks about Islam, Mrs. Clinton leveled an attack that might have shocked the political world in any other campaign: In addition to calling him a "recruiting sergeant" for terrorists, she accused him of giving "aid and comfort" to the Islamic State with his campaign oratory.

Not surprisingly, the Republican nominee returned fire, arguing that ISIS terrorists are "hoping and praying that Hillary Clinton becomes president so that they can continue their savagery and murder."
At a certain level, this seems like predictable campaign posturing in the midst of a competitive presidential campaign. When the public's attention turns to national security and terrorist threats, it's only natural for a candidate to say something along the lines of, "The bad guys would much rather deal with my opponent than me."
But isn't this a knowable thing? ISIS won't get a vote in the American presidential election, but isn't there independent information that offers some sense of their political preferences?
There are a couple of ways to examine the issue. For example, one could note, as many have, that Trump's platform and campaign rhetoric is consistent with what ISIS wants American leaders to say on a conceptual level. For ISIS, a key goal is to convince followers and would-be allies that there's a war of civilization being waged, pitting Islam against the West. The Republican nominee's endorsement of policies such as torture and Muslim bans has the effect of fueling ISIS propaganda.
The Washington Post's David Ignatius noted a few months ago that Trump's "polarizing rhetoric on this issue may be the best thing the Islamic State has going for it, according to some leading U.S. and foreign counter-terrorism experts."
But we can take this same line of thought a step further. Foreign Affairs published this interesting piece in August:

Analysis of ISIS chatter on social media and conversations with 12 current and former supporters of the group do indicate that ISIS strongly prefers Trump over the Democratic candidate, Hillary Clinton. When asked to explain their preference for Trump, interviewees offered several reasons. First, Trump's anti-Muslim rhetoric plays into ISIS' narrative of a bipolar world in which the West is at war with Islam. Second, ISIS hopes that Trump will radicalize Muslims in the United States and Europe and inspire them to commit lone-wolf attacks in their home countries.Third, ISIS supporters believe that Trump would be an unstable and irrational leader whose impulsive decision-making would weaken the United States. And fourth, ISIS subscribes to the prophecy of a "Final Battle," to take place in the northern Syrian town of Dabiq, in which the caliphate will decisively triumph over its enemies. Some ISIS supporters believe that Trump would lead the United States and its Western allies into the apocalyptic clash they have been waiting for.

The piece concluded that ISIS's supporters "say that a Trump presidency is exactly what they want."
TPM had a related report in June, adding, "In some quarters of the dark internet, where supporters of the Islamic State and other extremist groups linger, the presumptive GOP nominee has emerged a rallying point of sorts. To them, he is the 'perfect enemy, as one Islamic State defector told a researcher interviewed by TPM, and they are using his posturing to advance their own agenda, according to another analyst."
While the GOP presidential hopeful may believe ISIS terrorists are "hoping and praying that Hillary Clinton becomes president," the evidence appears to point in a very different direction.