Pantheon's ult shouldn't work like this

As a semi-Raka enthusiast (I can't call myself a main just quiet yet), I don't understand how Pantheon's allowed to cast anything if he ult's directly on top of my Equinox. Apparently you can cast abilities/have them buffer so as to have them immediately fire off as soon as you land, somehow bypassing the AoE silence. How the hell should that be allowed? Why would it be coded like that? Shouldn't it be coded as a blink? Like if you blink onto Equinox you'd be unable to cast anything, regardless of any ability buffering. If Shen teleports to somewhere on top of Equinox, he's silenced. If Katarina blinks onto Equinox, she's silenced. If someone uses the Summoner Spell Teleport and you cast Equinox under it, they're silenced on arrival.

So why isn't Pantheon affected by it if you pre-place Equinox where he lands????????