I think he's clearly mentally ill, but calling him a terrible human being sets a pretty low bar for what makes someone a terrible human. JMO
What makes you say he's mentally ill, Dr. Rusty? He came across as pretty coherent in his interviews - though he lied a lot.
To the extent anyone can be a terrible human being (outside of terrorists, murderers, violent/sexual criminals), I think this episode is a pretty good example. I mean, in addition to orchestrating a fake hate crime, he went to the station to ID suspects, and when he got there and saw it was his accomplices, he didn't ID them. Impliedly, if it was two guys with MAGA tattoos, he would've sent them up the river.