Gave him a brake test. He failed.
Sorry, that's just irresponsible. Of course no-one should be tailgating, wheelsucking or anything else, but a 'brake test' sounds like a rapid slowing down to me. If the rider behind you failed that test, well what else did you expect? How do you know that rider took your intentions to heart rather than jumping to conclusions about the way 'other cyclists' all ride?
If someone is wheelsucking, just slow down more and more until they get the point. There's no need to reduce your level of safety or that of the person behind you unnecessarily.