She’ll show up and when she shows signs of going down, there will be some kind of *security threat* that will shut down the debate and have them both hustled off stage within seconds.
It maybe someone who *sneaks in* with a gun. A suspicious package found somewhere. Maybe even an actual small blast outside the building. Someone claiming to be a kook with a knife. A power outage.
The options are endless.
Then they can claim she did show up and try to debate him but the debate was shut down against her wishes and she had to be removed for her *safety* or *protection*.
They’ll figure out some way of blaming it on the “alt-right” if they have to hire some starving actor to fill the role.