Here is the descent profile for Soyuz.
At 08:53:30 the speed is 7.62km/s and touchdown is at 09:14:39.
Over 1269 seconds the object sheds 7.62 km/s. Kinetic energy is $.5mv^2$. So that's 29,032,200 joules per kilogram.
29,032,200 joules/1269 seconds = 22878 watts. Over that 21 minute interval I get about 23 kilowatts per kilogram.
According to the descent profile, Soyuz descent maximum g load is around 4 g's.
I am trying to find the descent profiles of the Apollo capsules. They would enter the earth's atmosphere at almost 11 km/s. But so far I haven't been able to find descent profiles that give altitudes and speeds at different times.
In the scenario you link to I get max speed of 4.52 km/s at about 71 km altitude. Impact is 117 seconds later. For this I get 87 kilowatts per kilogram. More than triple of the Soyuz capsule. This is with a 1.85 meter radius, 6500 kilograms and a drag coefficient of .5
Increasing the radius to 2.9 meters, max speed of 4.5 km/s is reached at about 79 km altitude. Impact is 185 seconds later. Over that 185 seconds the capsule endures 54 kilowatts per kilogram. More than double the Soyuz.