You're mostly right, but his particular thing actually is safe. The water they are releasing is very very slightly more radioactive than normal water, but it's so diluted it is harmless. As said by another commenter, if you only drank the water they are releasing you would have the equivalent extra radiation exposure as a flight across the US, or an x-ray or 2. And they are releasing it slowly into the entire ocean, it legitimately will be safe.