Being miserable, and pissed off, is his act. Let him stay.
Yes, its his "thing." A typical Walter posts reads:
"You're a fucking idiot. You stupid asshole. You are probably tiny, you little shit. I hope you get HIV and die."
Walter is really obsessed with HIV. He always wishes it on people. I am unsure why he is so obsessed with this disease. Why not an a stroke or a heart attack? He needs to mix it up a little. Something like, "I hope you have a massive heart attack and die."