I like the response to that.

Many years ago I had “You'll never work with us again if X” from a company, where “X” amounted to expecting them to keep their side of an agreement wrt payment terms, to which I enjoyed responding “Oh, I insist on X. Whether I work for you again is not entirely your decision to make. I won't be doing BTW.”. A couple of months later they asked me to look at something and were surprised when I didn't jump to make myself available… They were also upset that I wouldn't give them contact details for other people I knew who could help (I did offer to pass details out to my social circle, but they said to not bother myself - presumably they knew I'd include warnings with the job spec!).