I'm going to have to put most of the blame on the PC12 guy. Yes, the lady in the tower (who I've noticed gets into the weeds fairly often but usually manages) screwed up, but who's flying the d@mn airplane? The part of the recording that scared me the most is when the proximity alert went off you could hear the guy in the background yelling and she went Walt Disney. While a CRJ200 is small, it's got lots of lights, all of which were on, and that guy in the PC12 should be extra vigilent knowing there are airliners whizzin by him at 120 kts before taking the runway. It's normal there, he should have known better. Kudos to the PSA crew, both good guys, who reacted quickly and saved it by a hair.
BTW the controller was "retrained" and back in the tower cab within a few days...got to love the gov't.