Tower don't remove Duskblade Proc?

I understand that the item says "if seen by enemy champions" but that seems dumb to me that a Zed/Kha/Talon/etc sitting under an enemy tower split pushing still gets to have his Nightstalker proc when the status bar icon itself says "has recently emerged from the shadows."

Umm, no, he hasn't. He's been under our bot lane tier two tower, in clear view, for 10 seconds.

Same for like ranged like MF. She's sitting there hitting your tower when she sees you walking back to lane and Q bounces off a minion and gets the proc. Again, she's been sitting under your tower, in plain view. That just doesn't make sense that she doesn't lose that passive when under a tower. I can understand not wanting minions to remove it, but towers? Really?

If towers are able to see invisible champions, something most champions can't do, you'd think they'd also remove this "unseen" passive proc. Obviously it should still have that wait time so if they run out from the shadows a dive you under towers, that they still get the proc. But if they are under your tower for 5+ seconds, they shouldn't have it then cause they literally aren't unseen.