There is some consideration for other patients who may die due to not getting an MRI in the meantime

They gonna to get an MRI while the guys corpse is stuck to the machine?

Again, it isn't an instant-off button.

Only good for removal of any metal-adorn victims and unintended metallic objects ...

The dude suffocated. You don't need anything near "instant" to prevent that.

Edit: Since apparently some people need reminding, per the article he had time to say goodbye to his wife before he lost consciousness, this wasn't some liveleak skull splat type thing.

The chain apparently caused him to be hurled across the room. We don't know how he died, but given the inverse square law, the possibilities are quite grisly.

He was wearing a twenty pound necklace. In a magnetic field that strong? His throat was crushed, likely instantly.

Do you have a source for that? The BBC just says "a medical episode" of which he died later.

Multiple heart attacks.

That I can well believe!