ok to eat lovers of animals like caribou

Dude. It is most certainly not okay to eat people who love caribou.

But yeah you're right. But also up North where the polar bears live vitamin toxicity might not be your only issue. Protein poisoning could be an issue, if you didn't have access to any carbs or fat (caribou, or reindeer as we like to call them, are suuuuper lean usually).

Also known as "rabbit starvation."

Rabbit starvation, also known as protein poisoning, mal de caribou, and rabbit malaise, is a form of malnutrition that arises when someone eats protein with too little energy from carbs or fat for too long.

https://optimisingnutrition.com/rabbit-starvation/