Like so many other things in life, the decision to use mercury intensifier is a personal choice, and individuals who choose to use it are responsible for the consequences to themselves and those around them. Yes, the stuff is dangerous, and yes, it can be used safely, but one has to know and deal with the risks.
Many years ago, I was in a workshop with a well-known photographer who uses mercury intensification extensively. He did a demonstration for us, and the results were amazing.
On the other hand, the man was in his late 60s and had been using it for years. He had a strange cadence in his voice - long pauses that suggested some kind of struggling mental process. I'm not a physician, but if I were, I might be tempted to suspect a correlation.
My choice is to try to expose and develop my negatives so that I don't have to resort to mercury intensification or other forms of negative torture.