SoggyShorts
Mathematician par Excellence
When I taught English it was admittedly many years ago and just ESL for little kids, but one of the most important distinctions in English is emphasis.I agree. Whether or not this is grammatically correct, it would be cringeworthy to most English teachers.
Unlike tonal languages and somewhat different from romance languages you get sentences like
"I did not steal your red bandana"
Where if you emphasize any single word either through volume, a slight pause or in-text by use of bold you get a totally different statement.
Since the use of bold is somewhat garish the arrangement of words can be effectively used for emphasis in the OP's situation, or through a double negative as @Aritra explains below:
I believe that "No one in the audience is not amazed" does not mean the same as "everyone in the audience is amazed." It moves the emphasis from characteristic to quantity. With "everyone in the audience is amazed," the natural stress is on amazement. "No one in the audience is not amazed" emphasizes the significance of quantity of persons being referenced. It shows that no one was unaffected (which is still not the same as everyone being affected, here we go again).