Can humans eat the sunflower seeds that's made for birds (bird seeds)?

I was shopping at a home improvement store and seen two employees talking and eating sunflower seeds as another employee was fixing a ripped bag of sunflower bird seeds that had fallen on the floor. It does say on the bird seed bag "Not For Human Consumption". But why exactly?

Can humans eat the sunflower seeds that's made for birds (bird seeds)?
The sunflower seeds in the bird food have not been protected from disease and have not been cooked
Reply:because it fuks with the digestive track....