Yes, that's crazy. They say up to 1 MW electric which would mean (33% efficiency) 2 MW of heat to get rid of with air cooling. Later they mention facility heating which sounds more realistic, I guess?
https://www.generatorsindustrial.com/products/1mw-diesel-gen... has a simple radiator.
but then the heat profile is different I suppose, and the efficiency doesn't depend on being able to shed heat.