One detail mentioned by Huazong:
Hu was asked to leaving before the live streaming began. But journalists had already entered and witnessed the shocking scene.
I tend to believe that Xi didn’t publicly humiliate a former top leader. This is not logical in any senses. The key point is the reactions of other people in the congress.
The apathy of other party colleagues is truly breathtaking. They are likely to be unaware of what is going on, fear and numbness keeping them from looking away. This is indeed undignified.