Feels more like a problem of simple manners to me. The easy and proper thing to do for Katz is simply take notes and wait until the end of the presentation to

Feels more like a problem of simple manners to me. The easy and proper thing to do for Katz is simply take notes and wait until the end of the presentation to make his counter points during the q/a session. Interrupting someone in the middle of a presentation just makes it harder for the speaker to continue. The speaker is going to be more flustered and the flow and presentation will quickly degrade because he/she is going to be second guessing everything that he/she was going to say. For some speakers, one heckle turns them from an OK speaker to a bumbling mess. It's also going to have a chilling effect on the user group. Who's going to want to volunteer to do a presentation after this?