2. Doing satire about blackface in the 00s was about as timely and relevant to issues at the time as making satires about railway tycoons would have been.

The examples of blackface among American politicians as well around that time (and I'm sure continuing) are abundant. It wasn't just JT, and IASIP was right to call them out on it in the satirical fashion that was relevant at the time. It's not their fault that some of the audience they reached were idiots that took it as "haha blackface funny" rather than "haha idiots that do blackface seriously are fucking idiots". We've seen through the whole run of their show how some fans have and continue to miss the point that these are assholes and you're not meant to want to be like them or do the things they do.