Coldbrew is a thing and done right it brings out a refreshing sweetness. Also iced coffee. Bad coffee is bad hot or cold.
I would rather have room temperature coffee than a cold brew usually though. I just did not have good luck with it so far
This is a myth. Bad coffee tastes better when hot because your sense of taste is dulled - reducing bitterness. Also, at higher temperatures, aromatics and volatile compounds are more airborne, improving the smell of coffee. Good coffee is better enjoyed around 60-70C
Regardless, I would say it’s an objective fact that good coffee is ruined at room temperature. It still tastes fine, but no where near as good.
What especially irks me is that they could have just heated the stuff in a microwave [1] to 50°C and have a much better test.