I used to work at Google adjacent to this stuff and A) you wouldn't boot up a whole VM for this, on a phone, that'd be very wasteful B) there's much simpler ways to provide the same guarantee.
So in general, just would avoid labeling the quality of other people's takes. You never know who is reading yours
I agree there are currently better ways of doing this (because as you mention the resource/protection trade off for this technology on this application is sub-optimal), but the context here is as an example on HN where the data privacy is obvious so I didn't have to write a whole paper explaining it.
Its "not even wrong", if you had a million monkeys on a million typewriters with a million trillion millenia, still, none would come up with a paper long enough to explain how that'd help anything (ex. trivially, microphone)
So in general, just would avoid labeling the quality of other people's takes. You never know who is reading yours