Pure unadulterated crap. We have to destroy parts of the earth in order to save it? Nonsense.
The research posited 100 Hiroshima sized bombs with an effect on global temperatures. India and Pakistan aren’t likely to use anywhere near that many, if they even have that many, in a nuclear exchange. The effects on temperature would be very little as a result.
Anyone alive in the 1970s, though, has effects in their bones of the open air nuclear testing by China at the time. Radiation travels.