Cannot set transparency of the torso?

I was trying to make a window that hides players behind it by exploiting the fact that non-opaque pieces of glass don't render non opaque objects behind them. I made a semi transparent part, and had a non can collide part behind it that sets anything that touched it to 0.001 transparency. When you leave the part, using touchended i set the transparency back to 0. This works totally fine, except for the fact that the torsos transparency doesn't work correctly. it doesnt get set, even when i set it using the properties window of roblox studio. My best guess at why is that roblox resets it automatically. So how can I get around this?

To replicate:

Make a part with material glass, and make it semi-opaque. Put a part behind it that when touched sets anything touched to transparency 0.001. You should see that if a character (at least with no accesories, just a blank roblox character) goes behind it, it will disappear except for the torso.

I did not test with the R6 Torso but the R15 UpperTorso worked for me in my code.

game.Players.PlayerAdded:Connect(function(Player)
local Character = game.Workspace:WaitForChild(Player.Name)

local UpperTorso = Character:WaitForChild("UpperTorso")
if UpperTorso.Transparency ~= "0.01" then
UpperTorso.Transparency = "0.01"
end
end)