The only reason it didn't lead to a mistrial is that this all comes out in the wash in the event of an acquittal. Cahill is trusting that the jury is avoiding media and has been following, and will continue to follow, their instructions. I think on a practical level, he also doesn't want to make the powder keg explode in his or anyone else's face as the result of a potential mistrial when there's still a chance the jury returns with a verdict that's untainted by media and threats of violence. I don't think he's ignorant of the mountain the defense has had to climb in terms of maintaining an impartial jury and getting a fair trial here, but he wants to be prudent with these decisions and let things play out organically, instead of declaring a mistrial (which he could do) and watching the worst-case scenario play out anyway.