How to handle a paper by a reviewer who wants to be paid?
First of all: Is there a rule that you need to be available as reviewer if you want to publish in that specific journal? People decline reviews for all sorts of reasons (often lack of time, which may or may not be the case), and I never heard that somebody got "punished" for that.

Your reviewer wanted to get paid. It is very unusual to pay reviewers, but on the other hand, it is not per se unreasonable or offensive to ask for compensation for work.

I would see it this way: Either you establish a general rule that authors must be available as reviewers or you accept that some people do not review papers (although they publish).