Well, if it's on his own turf he can be certain about security and where the guard's loyalties likely lie. A certain Russian Ambassador probably would have most certainly benefited from going to an art exhibit held in a more... Putin friendly location. Harder for some random Islamic fuck in a nice suit to just walk up and say he's cool and get in to position to go full Jihadi, just sayin'...
Also I'm with you @Raver, he's a total shot in the dark. Though I would say I'd rather take said shot than *glow* in the dark as the result of Hydrogen Hillary's likely foreign policy. Dumb bitch'd kick the bear in the balls with bladed steel toed boots at the drop of a hat triggering the nuclear apocalypse. NOPE! NO WAY! [Vehemently Votes Trump on that matter alone ].