I think it’s more complex than that. It’s the ability to remove heat, rather than the ability to absorb heat, that matters. The iron block will absorb more, but will get hotter and hotter unless the cooling system can reject that heat to the environment.
Simple V-8 without oil cooling, and an archaic radiator, is going to overheat running at 75% power. Like a long hill.
That turbo 4, with an integrated oil cooler, and better cooling system design, will be running at 60% power, same HP output on the same long hill, and is better able to manage the heat load because of the design of the system.
I’ve towed with a turbo 4*, and the water temperature was constant, but the oil temp (it was a basic turbo, no water cooling like the truck in question) ran about 15-20C higher than normal. In the car’s favor was the thermostatically controlled, and relatively large, oil cooler mounted adjacent to the radiator.
It handled sustained high power output for hours without overheating, even with a system that was primitive in comparison to the design of the truck in question.
* 1985 Volvo turbo wagon. Turbocharged, intercooler, 4 cylinder with a manual. Total HP was 165. A lot for the time, but a paltry amount by today’s standards. Towing a double axle U-Haul with a piano and furniture. The trailer weighed about what the car weighed. It was a lot of weight for the car. Full throttle, full RPM, full boost, to get it up to speed, and a good amount of boost/throttle to sustain the speed. The car had both a boost gauge (factory installed) and an oil temperature gauge (genuine Volvo accessory that I installed). I owned the car when I lived in Virginia, and in Colorado, where it was frequently driven in the mountains. It was an education in coolant vs. oil temperature and the effect of heavy turbo loads on oil temperature. It was also an education in how well a turbocharged engine handled rarified air in the mountains.
