Made me laugh. Before we get any deeper into this, I'm not really a part of the internet troll culture. I mix it up a bit on Twitter, but have never been to any of the chans, and limit my political analysis to some fairly milk-toast sites. I do love me some Pepe, but that's just because...I mean, look at that face! Don't know why but the utter inanity of Pepe combined with the high stakes political game just busts me up every time. (Perhaps not every time, but you get the idea.)
What follows is an outsider's analysis and not based on any inside information. Nor is it so much a call for action as it is a prediction based on past performance.
With that out of the way, let's do some nonstandard analysis and predictimicating. We all know that the standard analysis will consist of long winded versions of the playground "Uh uh!" and "Yuh huh!" arguments. Instead, let's look at one potentially huge ramification of this random guy yelling one random word into the short silence between sentences.
This guy just opened the door for every alt-right troll to turn the tables on the left. They've established that shouting during Trump speeches is a legitimate form of protest. That means that the alt-right can shout/protest Hillary speeches by yelling, "Pepe!"
Will she bar them from entry? How? Right now Hillary's crowds are so small they'll take every warm body they can get. Any 'net troll who wants to up his game can get through the doors and sound the call for freedom during her speech.
One shout is a pin-prick, but if this happens over and over at her events, it's going to become the slow drip of Chinese water torture. She can't respond to the shouts; any man with the stones to protest like this will be more than capable of engaging in whatever rhetorical thrust and parry she brings to the show. Heck, even responding grants the alt-right troll a legitimacy that she can't afford to grant him. There's no good response but having security make the protestor quietly disappear*.
How will they respond to that? If history is any guide, with an iron fist. The campaign will have to start vetting entrants and that's going to suck all the way around. They'll drive away more people, spend money, slow things down, aggravate her loyalists through un-necessary checks.
*Take that however you choose.