That is a good question; if you get a hung jury and they retry, if this kind of stuff is inside you, why take the risk?
This is probably why he wasn't considered a threat. I wonder if the "shank" that was found on the guy earlier was just a common item that could considered a weapon - sort of like at the airport with fingernail clippers.
I don't see why a guy out on bond would bother to carry a shank into the courtroom - what would he hope to gain? Of course, it doesn't make sense that he would shoot people in the courtroom today either since he could have just disappeared into the night and would have been a low priority manhunt.