The interaction between Soraka's E and Yasuo's R

Basically, Yasuo's ulti can be separated into two parts. First, blink to the location where targets are airborne. Second, suspend targets airborne for 1 second, slashing targets and he doesn't deal damage until targets landed. For the second part, the damage that Yasuo will deal to the target can be mitigate before the targets landed, for example, like the target was swallowed by Tahm Kench before the target lands, so there will be no damage deal to the target. Another way, before target lands, Yasuo was CCed and interrupted. For Soraka's E, it can interrupt the channeling spells, like Fiddle's ulti, Kat's ulti, Zac's E. Since the second part of Yasuo's ulti, which is more like a channeling process (I am not sure if it's a channeling spell), Soraka's E, the silence should be able to interrupt the second part of Yasuo's ulti. So to my understanding, if I land a silence area to where Yasuo will blink to, Yasuo will blink to the target location but he won't suspend and slashing targets and deal damage to them as if he was CCed during this process. Some times, I knew my teammate would be blow up and Yasuo would ulti them, I landed the Silence area around my teammates, Yasuo was able to blink to them (there is no doubt with this part, as I didn't land the Silence area around Yasuo), but he is still able to suspend them slashing them and deal damage to them in the Silence area.(while this part of actions can be interrupted by CC, why it can't be interrupted by silence?)