Did I misread or did you write that she was 20 years old at the time? That is THE time to tell the world to fuck off. Also, this attitude can be very healthy when it comes to not getting pushed around in other areas of life.
Her mentioning about death and nothing really matters is really FUCKING TRUE. As long as you don't hurt people on your way out you're doing fine.
Words on a shirt can only make people think.
p.s. kids don't give a good goddamn what someone has on their t-shirt, they just want more candy or rides