This was a planned event (planned for months) to show unity around the premise of religious liberty, something Pope John Paul 2 fought for in his life. This was the 100th anniversary of his birth I believe.
Understandably these fascists trying to bring our country down don't believe in religious liberty, (and certainly not something the Catholic church seems to believe in) but that's their own problem, and hasn't been echoed by every Pope.
The president should not be allowed to be killed by a bunch of nut jobs, he's the president of the United States.