Any source? That would be a news to me.
It was said here in the forums somewhere.
Here is the source in question: https://forums.puri.sm/t/sim-card-killed/19464/27?
It doesn’t say what you claimed. It says the pin stays energized when the tray is taken out (which AFAIK is true), not that it stays energized as long as the battery is in. Turning the phone off will turn that pin off too.
Oh, well then I apoloize for my misremembering