Trauma memories

One way atheists routinely attack evidence for miracles is to claim that eyewitness testimony and memory are notoriously unreliable. In light that of that stock allegation, it's striking to read evidentiary appeals like this:

Witnesses report Roof sat with attendees of the prayer meeting for an hour before he turned his gun on them. Three men and six women were killed. Three people survived. 

One woman, who said she was as cousin of the church’s pastor, Sen. Rev. Clementa Pinckney, told NBC News late Wednesday night that the shooter reloaded five different times and told a survivor...
- See more at: http://www.patheos.com/blogs/progressivesecularhumanist/2015/06/charleston-church-shooting-was-about-race-not-religion/#sthash.iUutcQwC.dpuf

Keep in mind that this was an extremely traumatic event. But haven't we been told that makes testimony less reliable? For instance:

People’s memories for traumatic events are – like their memories for more mundane events – easily distorted. Importantly, memory distortion for traumatic events appears to follow a particular pattern: people tend to remember more trauma than they experienced, a phenomenon referred to as “memory amplification.” 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4337233/ 

That presents a dilemma for atheists: they can't discount eyewitness testimony and memory in general without discounting the testimony of observers who witnessed the shooting.

Conversely, they can't vouch for the testimony of observers who witnessed the shooting without conceding that eyewitness testimony and memory can be trustworthy.

I think there are two reasons that atheists are so credulous in reference to this incident:

i) They want to be seen as champions of civil rights. Siding with blacks. Opposing racism.

ii) They want to establish that the crime was racially motivated rather than religiously motivated. The testimony of observers who survived the attack helps to establish that claim–especially initial reports, before we had additional incriminating information (e.g. Roof's "manifesto").