I think You missed the point, or did not read my entire post.
The point is that Presets in media encoder do not allow for creating passthrough audio. (like for video settings – “based on source) hence the need to create separate preset for every audio channel variation you media happen to be.
What is strange to me is that while such a preset cannot be created within AME. Ingest presets provided with premiere out of the box (cineform proxy presets) – are able to do that. Whatever you throw at them they will perform audio encoding based on source file – (no need for specifying number of audio channels). So Premiere has that capability, But presets to acheive that cannot be build from end user perspective. Either that or im missing something.
as You mentioned The video You linked does not go into audio.