The blur is actually insane amounts of noise reduction, it's not an attempt at bokeh, I think! You can tell because all other shadows are just as blurred out.
I think that it doesn't look flat just because of the flash, but really as a mix of incredibly severe noise reduction as well as a ton of dynamic compression necessary to keep the background in roughly the same exposure.
He says it’s “Portrait mode”, so it does have the fake bokeh on the background in addition to any smoothing from night mode denoising. That’s why he also mentions the depth map for the fuzzy hood.
