All of your reasoning is plausible. I'd like to add one more theory...
The MSM may be ignoring this on request from the FBI. Also, most reporters were saying this was a "dead" story last Monday. The AP has only released 3-4 articles which is what most reporters look for nowadays. As far as why the FBI might request it to be downplayed I see 2 possibilities; 1.) Matters of National Security - perhaps this event lead them to learning of the threats in NYC? or 2.) Perhaps they have found links and don't want to expose their ineptitude.
IMHO there is much more to fear from Americans thinking our gov't can't keep us safe from these things than Americans taking it out on Muslims and burning down mosques and such...
This presumes that the MSM would obey a request from the FBI in the interests of national security