You brought up his dan level when in fact he couldn't have more at age 21. There are countless of 6-9 dans in TKD who don't even come close to Rogans technical level and power generation. Chuck Norris, Joe Lewis - just about any karate or TKD legend from the 70s or the 80s, do not have his technique.
Name one 9 dan that is even in good enough health to kick a bag that hard. I can promise you they were doing just as well when they were 21-45.
His power and technical level isnt anything special For his size, age, and rank.
Benny the jet was using equal level tech and kicked hard enough to do damage to MT fighters.
Emilio narvaez was kicking properly as well.
Bill Wallace had significantly better roundhouses.
We have guys at our school ages 16-35 who move the heavy bag the same way he does at 1st gup - 2nd dan.
We have higher ups who can kick harder and better.
We also have 5 dans who cant train like they used to and are outclassed in sparring by the young guyd of lower rank
We have 1st gups who are 21 outkicking 6 dans who are 50.
Youve been told by 5 or 6 karate/tkd all from completely different areas and experiences guys that his power and technique isnt anything special for his age/rank, because it isnt. Hes making hard contact and moving the bag
He isnt knocking a 200 lb bag to the ceiling or breaking trees,
Youre carrying a torch that isnt there bud.
Not all Black belts are equal in any style. Theyre just a belt. A better indicator of hard work and commitment than overal talent. You seem to have a hard time with this concept.