For the most part, I'm with you. Some of the reactions were a bit...off. I'd tend to try & give some leeway given the situation though. As you mentioned, the Walt Kelly reference - could be construed as a place where Nelson was looking for levity. Really hard to tell with his delivery as well & it's much easier to sit back after the fact & be able to discern his temperament more accurately. Live & perhaps without a great familiarity with a speaker's background, things are much tougher. I've certainly been at events where there was the sort of awkwardness of people not quite getting the true tone. And certainly as you mentioned, what came before can factor very heavily in the mindset of the audience & that absolutely colors the reception of the message.
I actually see silver lining in to the "real thing" applause portion as well. It seemed like it was more on the naivete part that brought the clapping. Certainly there's a poignant element to that given the course of Englebart's career. But by the same means, I tend to see some reason to celebrate that quality as well - the innocence of not having been corrupted by the cynicism of the world. Brilliance sometimes only comes at when there's an absence of knowing better - to be unencumbered by what everyone "knows can't be done."