Most people, upon learning that an entire room full of overachieving Ivy League students didn't do the reading for class, might take the opportunity to reflect on the workload or their teaching ability. In fact, the other 3-4 TAs decided to summarize readings for the class if they weren't already. Not Papcke!
Her discussion group was anemic. She needs some work on facilitating conversations. Even if she ran great discussion groups, why would you want to be disadvantaged compared to other TAs who don't take attendance and try to be proactively helpful? Your grade depends on you finding another TA.