I would simply not do anything further with this person at all, under any circumstances.

You had a bad feeling from the beginning about this guy. Your first instincts are your brain trying to tell you something. Listen to that instinct and you won't have to deal with these people.

I have found that the big clue that someone is trouble is if they are "pushy". When conducting calls or interviews with people, I immediately weed out pushy people. This is an indication that they are overly self-centered and won't consider your needs and will have unreasonable expectations. They won't consider your need to get paid and will be a drain on your resources. If stuck with someone like this, re-direct their requests.

Don't be rude, just don't get pushed around. Don't lie either. Tell him the truth fairly and kindly and maybe he won't treat people this way in the future. Telling the truth politely is not rude. Just remember not to phrase things aggresssively.