I am guessing the idea is to induce terror in the holder such that, if they did not intend to hold a vial of Co 60, they would not mess with it further. It conveys the appropriate level of danger, if not an appropriate set of handling instructions.

Edit: So I looked it up and I misunderstood: if you can read that (especially by the blue glow) then its rapidly killing you. I really don't understand how dangerous some radiation is lmao.