Well, not sure. The first paragraph seems to suggest that keeping your body “cool” with a “cool environment” will increase your capacity and ability to push to new levels. So I’m not sure it’s actually contradictory to what I’m saying.
Heat Training itself does not necessarily mean just “training in the heat.” As I said, it helps your body adapt to performing in the heat. There are mixed studies on whether the acclimation actually increases your capacity to do work in cool environments.
Specifically at 1:37:00. In the first study those testing in the heat showed no improvement over the control group when performing in cool conditions. And then a few minutes later he mentioned a different study that suggested there was some improvement that could be measured even in a cold environment, but perhaps we’re saying similar things with different terminology. Either way, I guess your mileage will vary and it’s all very individual. If you can hit the same power numbers and for the same duration with the same RPE and recover as consistently in the heat than you can in cooler temps than I’m sure it would be helpful.