First things first, is he actually making a feature? And it’s a bad career move because everyone in theatres were laughing at the trailer in a “what a dumb piece of shit idea” kind of way. For a trailer it was fun, but a feature-lenght film? Yeesh!!
I think you get the wrong impression of why people laugh. In the case of the faux trailers, most people were laughing because of the nostalgic feeling from watching these old fashioned trailers, and remembering how silly and over-the-top some(most) of them can be. And also others, including myself, may laugh when generally overexcited. Now, personally I think the idea behind Machete is brilliant and I would go see it in a heartbeat -including many others.
Try watching a trailer with other people that actually THINK that the idea behind the movie is dumb. What do you usually hear after the trailer? Silence or whispers in the theatre about how dumb the movie actually looks. I’ve never heard an audience laugh at a trailer when they didn’t like it.