Exactly. If all you wanted to do is add the mics, you'd never have masked Biden. And a masked Biden is required to get the mics to go behind.

A greenscreen Biden is by definition going to be masked and amenable to this oopsie, but someone would have to purposefully and meaningfully go out of their way to create this fuckup if this was a legitimate shot with some mics added.

But also, why the fuck would anyone add mics in the first place??