At 20 Gravitys a human would die of heart failure instantly. and his spine and legs would snap. And a average human head alone, would weigh 220 lbs.
I am not certain that is correct. Plenty of people survive aircraft wrecks in excess of 20 G's. They dont die instantly from heart failure, and many dont have snapped spine and legs, although many more do sustain spine and leg injuries.
20 gees for a second is survivable (maybe) an average ejection seat only causes about 10 for that same reason.
To be standing in a 20 gee gravity like the gorn did would be fatal .According to my egress instructors in the USAF.
( at 8 gees most people start to black out because the blood starts pooling in their lower body)
Being seated and wearing a G suit spreads the forces around and they can be tolerated briefly.
To be standing and receive the same trauma, would leave you a puddle of jelly.
Imagine somebody throwing a Volks Wagon on your shoulders while you where standing,and imagine what that would do to your legs, and spine.
I weigh 235. At 20 gs I would weigh 2,700 lbs.