"On one arm was inscribed Ax Ismael, a name whose significance has not been determined but might be a Biblical allusion."
A "BIBLICAL ALLUSION"? The biblical spelling, as we all know, is "Ishmael" and not the Q'URANIC form of the name that they quoted. Even allowing the possibility that the killer couldn't spell, sweeping this fact under the rug as a biblical reference is surely a noteworthy and unfortunate omission.
Given all of this mentally-ill killer's ramblings about "martyrs" and so forth, it's very likely that he identified to some extent with Islamist terrorists and killers. But given his Korean Christian background and well-documented lack of pretty much any social activity, it's extremely unlikely that he had anything at all to do with Muslims, the Q'uran, or Islam. The name could be an oblique reference to something Islamic, but it also sounds a lot like a username online or in a video game, and we know Cho spent a lot of time on his computer. "Ismail Ax" sounds threatening in and of itself.
Why not mention a few more likely explanations for "Ismael Ax" on his arm? It's possible that the New York Times is reluctant to have not one but two of its much-touted minorities in their diversity agenda, Koreans and Muslims, associated with this horrific crime. Maybe they were trying to forestall, in this age of mostly-Islamic terrorism, any chance that someone somewhere might link this case to Muslims or Islam, with which it is basically not connected. It may be a noble goal, but a newspaper should not choose its facts based on what some hypothetical idiot somewhere might misinterpret—they're supposed to be working for the rest of us! They should print the facts, regardless of their palatability or (slight) potential to be misinterpreted.