Well, a lot of other sources disagree with Dpreview then.
As for weather sealed and heat, what I mean is in 3 ways of heat transfer: conduction, convaction, radiation. Weathersealing reduce convaction to minimum, but it does not neccessary reduce conduction.
But how are you proposing to perform this conduction? Doesn’t sound like you are considering this like an engineer.
Sure you can cool the body... but you would still have to properly conduct the heat from the sensor to the body well. But bear in mind that even if this were the case, the path would be a two way street.
Say that you had thermal paste on the processor, and a food heat pipe connected to it leading it to be hard coupled to a copper body. Then the heat from your hands holding the camera, and external environment would also transfer heat to the processor. Additionally it can be a hazard of the amount of heat from the processor got too high. Like my old Mac used to get up to 100 C on a hot day before shutting I self off. It got fairly toasty.
I am fairly sure canon considered all the various possibilities, and converged on this.