I'm saying that, all other factors being equal, that stuff with a long half-life is less dangerous than stuff with a short half-life. To put it another way, "h

I'm saying that, all other factors being equal, that stuff with a long half-life is less dangerous than stuff with a short half-life. To put it another way, "half-life of infinity" = "not radioactive at all". Now, there are other factors involved (type of radiation emitted, what fission products appear further down the decay chain, etc.), but none of them are made worse by a long half-life per se. It's a scare term, pure and simple.