The regulations state terminal velocity, so at first glance the above isn’t correct (though I think you’re right, the idea that it falls from a standstill is ridiculous).https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/airworth/papers/human-injury-model-small-unmanned-aircraft-impacts.pdf
Looking at page 17 specifically, you'd need the mavic 2 to be travelling around 12-13m/s to impart 80J. The paper also states that 120J of energy transfer can lead to serious injury, and even death.
The mavic has a maximum speed of 20m/s. At maximum speed, and if it hit a person, there is a 200J transfer of energy. There is a 90% chance the person hit will die.
Simply put, you could kill someone if you really wanted to with a Mavic 2.
Just like how you can die walking on the road, being hit by a car, stroke, heart attack, random punch, falling glass from a building etc
All DJI needs to do is limit speed to meet the regulations
However, using the NASA TV calculator, an incredible DC of 0.7 and an immense cross section of 0.08m2, you get a TV of 60m/s, which is 1600J. As you say, enough to kill.
If you prefer more restraint figures, let’s go with the DC of a prism (to cause reduced air flow), and an insane cross section of 0.2m2. That gives us 32m/s or 460J of impact energy.
To get to 80J you need a TV of 14.1m/s. Even if it had a cross section of 0.2m (that’s 20cm Square!) and a DC of 5 (I don’t think that’s even possible), it would still have a TV of 15m/s.
The only way you get 80J with normal values is if the drone weighs 250g.