Protecting the vulnerable should be our highest priority. Problem is, it is almost an impossible task.
Mr Cain was a grown man and took whatever risks he chose of his own free will. As we should all be allowed to do.
Also, he went lots of places. Not just a trump rally. He probably went to the gas station and the convenience store and his office and his friends house...and everyone he saw also went lots of places. There is not one scintilla of evidence he got it at a trump rally or anywhere else.