Soraka Silence underneath Zhonya's hourglass [Gameplay]

Me Soraka played against an Ekko and his team. During team fight ekko got low and used Zhonya's. So I layed the soraka silence underneath him to prevent him from any use of abilites after the active time. But after his Zhonya's went off he instantly flashed or used his E to escape into his R. I am pretty sure that the silence area was perfectly timed, so normally he couldnt have escaped...