Sounds like he did this with the deliberate intent of making Republicans and conservatives look bad.
He probably realized he could go a little wild considering he's popular and has a lot of social capital to spend.
Yes, he used lots of flattery as JSojourner, probably in the hopes that everyone would side with him when his trolling sock puppets were exposed.
I wonder whether JSojourner is real. It's quite possible he was making fun of leftist Dems with that account too, though this forum is so far left they took it seriously.