problem with disabling the picking of a stack of items from a slot

I'm making a mod for a machine that creates a portal when you insert a crystal into a slot and press a button. I need it so that while the machine is running the player cannot take the crystal from the slot. I tried a lot of things, for example, creating an nbt tag in a block and trying to make a condition on it, such as returning a logical value when the tag = true.https://imgur.com/a/GxoipKS

But it doesn't work! Please help!