His point was that the headlines are different. I don't know what happened in the two events so I can't comment on how accurate the headlines are, but the headlines themselves categorized people upset with Waters as "hecklers," and the people upset with MacArthur as "angry." The negative connotation of "heckler" paints Waters as a victim of unreasonable malcontents. The other article calls those upset with MacArthur as "angry," implying he did something to draw their ire. The percentage of the crowd in question does not matter.
Again, I have no idea what happened at either of the events, or who attended. This is just an observation on the headlines of the stories about the events. It is possible the headlines are accurate, but I'm not sure how one would go about proving it, unless those heckling Waters were not angry, and those angry with MacArthur weren't heckling, but rather voiced their objections calmly and without disrupting the event (which I find hard to believe). They both seem to be about politicians facing people who disagree with them. One headline implies those people are wrong and the other implies those people are right.