Wrong.
Rainmaker doesn't use sliver iodide. They don't say specifically what they use but it maybe similar novel material that the UAE first used.
TiO2/NaCL shell/core nanoparticles
Because they're at nano scale they can stay in clouds much longer. Days, in fact. And they can absorb 127 times more water than standard NaCL.
https://avestia.com/RAN2017_Proceedings/files/paper/ICNEI/ICNEI_105.pdf