That is less invasive than making you blow. But there will always be edge cases.
Imagine a medical condition that makes it look like you are impaired. Now, you have to go to the dealer with a doctor's note to get this system disabled. Or when you want to rent a car.
Or, if there is a case when driving impaired would be better then the alternative. You and a friend are camping in the woods out of cell range, you both have some beers then one of you trips and gets a deep cut on the leg. Now you have to wait a couple hours before he can drive you to where you can get cell signal, hope you don't bleed out.
But the text makes it seem like they would position cameras toward your face and do analysis on impairment indicators like eye movement.