Although this angle is based on very qualified opinion and good research, it can be criticized on several major points:
1) There was no parachute? There was not retro firing rockets?
The method of maneuvering the blunt edge vehicle with internal weights, that these two gentlemen describe, was later used by all the Apollo re-entry command modules as well. But with Apollo maneuvering with internal weights was used high up in the atmosphere and closer to the Earth 3 parachutes were deployed all the way to the touch-down on water.
Although it is impossible to exactly say without proper calculations, the weights shown in the Mark 2 RV look too small to produce 180° turns at very slow speeds near the ground. Slower the speed, heavier the weights need to be. The weights shown in technical illustration are very small and they would had been effective only at higher speeds at higher altitudes.
Landing on water is hard, never mind landing on ground. To land on ground, RV needs to be slowed down much more than for landing on sea. Russian command modules that land on soil, apply both parachutes and retro firing rockets when few feet above the ground. Mark 2 RV never fired any retro-rockets to slow down.
2) Once canister with films was ejected, Mark 2 RV main vehicle was totally disposable.
There is no reason to salvage Mark 2 RV main body, most likely it would be dumped into either Pacific or Atlantic. Mark 2 RV main body would be falling too fast and least probably it would be aimed near the populated area, particularly with nuclear power source on board.
It is clear from the design that Mark 2 RV that it was disposable. It was firing the film canister in the opposite direction to that of the movement of the main body. That means that film canister would be slowed down relative to the RV and the Earth and touch the ground behind the RV. Perfect if you want to fly the RV all the way to ocean, while canister drops anywhere over the land.
3) Copper as heat shield? Crazy idea.
Copper's melting point is 1,085 °C. Assuming that Mark 2 RV was coming back from lower Earth's orbit, same as Space Shuttle, than heat on the shield would be similar at about 1,649 °C. That means both that copper shield would either completely melt away before reaching ground, or it would heavily deform causing unpredictable aerodynamic behavior.
Furthermore, copper is one of the best heat conducting metals and, because of that, it's frequently used as a heat sink on PC motherboards. Because of that copper shield would make interior of Mark 2 RV extremely hot. Exactly opposite of what heat shield would need to do and keep the interior cool.
4) NASA employee took a photo and lost his pension.
Allegedly, this is one of several Polaroid photos taken by one of the two NASA employees who attended the scene. There is a video on YouTube where this NASA employee talks about how he lost his pension scheme and how he now lives in poverty, because he broke his secrecy oath by going public about this incident.
Anyway, here is a full article for those who want more information:
Show Notes, John Ventre & Owen Eichler, Kecksburg UFO Solved? – Podcast UFO