(Do they really have those laws?!)Good point to consider!
But, the same state also has a law that it's illegal to fart in public after 6 p.m. on Thursdays, or for a woman to fall asleep under the hair drier in a salon...etc.
If the dye used is safe for children, I'd consider it safe for animals, too, and that's all I would use. It's water-based and will wash out, but I would just let it wear out.
Again, just for fun on one of them. I'd hate to cause a different-looking chicken to get picked on though, so I could be creating a problem here.
I'll think about it and check into it further. We'll see. If I do it, this'll be the first place I post a picture.