Prof. Stock is maintaining a very dignified silence which is probably appropriate when Prof Hines manifestly did herself no favours in utterly failing to explain her position in a way that the audience could begin to track.
I have my own thoughts as to why that happened but, even so - it's never a good feeling for anyone to have to reflect on quite why you failed so comprehensively to explain your ideas. It can be quite crushing so you're typically well advised to take a beat, reflect on what you're hearing and then take an honest assessment as to whether some of that criticism has some merit.