I only caught the second half of the debate, but I didn't think that Berg did that horribly. The main reason to take him out imo is just because 1) he's stealing votes from Biden and other non-Sanders Dems, which makes it much harder for a brokered convention to skip Sanders, and 2) he's proudly attacking Sanders which will only make the Sanders supporters angrier in the general. The media didn't seem to care much about Berg's past controversial statements until after the debate, and not that many people actually even watch the debates, so imo if the next wave of polling shows that Berg holds relatively steady, they'll forget that this debate even happened and legitimately try to promote him as the "best man to take on Trump" or whatever.
EDIT: nvm didn't see the NDA part, that was brutal.
EDIT #2: Saagar's bit on the brokered convention was great, but it's not accurate to call it unprecedented. Just in 2008, Obama won the delegates while losing the popular vote to HRC, and brokered conventions were extremely common pre-Great Depression. But if this became a brokered convention, it would be the most public brokered convention in American history, the electoral equivalent of My Lai hitting the American media.
EDIT #3: nvm again, loose on the facts, forgot that 2008 technically wasn't brokered but it involved HRC losing the delegates of two states she had won, which ended up inching Obama to victory. Apparently the last time it has happened was in 1952, so yeah almost 70 years later would be pretty crazy.