Maybe the castle is like, "I'M GONNA CRUSH YOU!! Nah, just kidding! You beat me fair and square! I am gonna crumble though, so you should, you know...probably get a safe distance away from here. I'll wait." X-D ;-P
But seriously, I like the idea of playing through a crazy rush out of the castle. I definitely wouldn't want it to be a QTE, but I could handle if running was automatic and I just had to control other actions like turning, dodging, jumping, attacking, etc..