Zahavasdad
It isnt remotely similar to the Shabbos Lamp. With the lamp it is on for the duration of Shabbos you just cover it with a safe cover to block the light which remains on. This is not much different than closing the door to a lit room.
The kosher switch, does block something but that in of itself doesnt make it muttar. The light actually turns on and off. It is in no way similar to the kosher lamp. “Blocking something” isnt a magic phrase that allows melacha to be done (though it often turns it into gerama which is still assur), many melachas invlove “blocking something” for example all you do when you shut a stovetop is block the flow of gas to a flame, it is still assur on Shabbos (and Yom Tov).
The way it works as identified on