That turn of phrase certainly is figurative. To me, "pissed on" is one of the most vivid idioms in the English language. Picture it in your mind. The family and former friends are desperate to help the man escape a wretched life. They surround him, hands outreached, trying to help. In response, the man whips out his penis and urinates on them. Then he walks away. Can you see it?
We hear and say "pissed-off" all the time. That just means mad. "Pissed-off" doesn't offer a mental picture like "pissed on" does. Despite the mental image image I'm trying to convey, the idiom isn't particularly vulgar. It's strong and vivid language though, it's not something most people would say every day. It's kind of reserved to describe the worst kind of rejection, dismissal and contempt.