This is a special kind of stupid. They're not recording silence, they're recording the ambient sound of the room. The entire point is that it's not silent, even if it is very quiet.
This is a special kind of pedantic. You literally said the same thing as them but with mostly unnecessary specificity and explanation and acted like THEY were the idiot for assuming people would appreciate and understand their metaphor. Nah dude, they explained it the way it was explained to them and they understood it and so did most people.
Totally, but the context is important. Everyone in that environment should (hopefully) understand that when they say silence, they don’t mean literal silence.
I think in context it is clear what the person was saying. When we talk about silence we mean the resting noises of the room. We don't mean if you cut the audio feed what you are left with.
And yes it is true. You get a sense of space from those tiny noises and how they echo and get absorbed.