You're totally correct, these nuts should
come with a warning.
According to the National Institutes of Health, abnormally high levels of selenium in the blood can cause a condition called selenosis, characterized by symptoms such as hair loss, garlic breath odor, white blotchy nails, gastrointestinal problems, irritability, fatigue and nerve damage. The effects of selenium poisoning are similar to the symptoms of arsenic poisoning, though symptoms may vary depending on factors such as the type of selenium ingested as well as the dose. Other symptoms of selenium toxicity include lightheadedness, facial flushing, tremor, muscle tenderness, liver and kidney problems and blood clotting problems.
And just one ounce of them have 776% the RDA of selenium. But other than all that, they're very healthy!