Well, notice one thing. They are looking a ways that "global warming caused by human activity" is being masked. This a common theme, they also decided in that oceans were holding the "extra heat" from human caused global warming.
It's speculation. It's not science.
I will give similar argument that I have given previously about space elevator and nano carbon being used. Which is simply that there would a lot of value for other applications of nano carbon than for space elevators. And Space elevators are a completely lousy driver for developing nano carbons. In other words it's wishful & useless thinking.

Now, as far pollution causing clouds. If we knew how this actually worked, then we could probably very easily control Global temperature- in other words global warming would be an even less problem than it is actually is at moment. Cooling the earth would like switching on the lights. And problem then at that point would be how can we warm up the Planet. And of course the most valuable use of cloud making technology would be to end droughts or simply increase rain so you didn't need to irrigate farm lands as often. In other words this knowledge would be worth billions even trillions of dollars. So if it could be known, it would have been known- unless you imagine that scientists are too dull to see this.
But like manufacturing nano carbons cable, it's not as easy to understand and do as people might imagine.