From history we do know that would be would-be assassin Arthur Bremer stalked Nixon, and then backed off (too much security?) and settled on Governor Wallace (paraylzing bullets) in a shopping center in Maryland. Some times these guys get cold feet but get real close to actually doing it, do dry runs, what not. Who knows what the guy might have had strapped to his person under that BDU. I doubt there was any metal detectors or pat downs at this particular event, and this was in the real heat of the Israeli-Hamas hot war in Gaza, he sure got there front row/center. There isn’t any doubt in my mind that NMH was already well into a jihadist mind-frame by that time.
That is why exposing his blogging publicly is so important, to see if he was sharing plans, doing this all on his own, or just monitoring a group posting of opportunities. I'd also hazard a guess that if his name came up on an FBI watch list his emails may have been monitored by NSA. It would be interesting to see if he had private key encryption software on his computer.