I, purrsonally, think that the guy has been punished enough for the incident. Most importantly his family has lost out on the love and companionship of their furry overlords.
If the RSPCA were to prosecute him I think that he will accept that he was wrong and pay any penalty that he has to. It will make the RSPCA look a bit more effective than they seem to be.
I don't know if he should get the cats back, there is no indication that this has happened before. If the cats were, prior to this incident, happy and settled and are happy to return to the household then it should be an option.
I know that some people will disagree with my opinion and that is not a problem. But I wonder how many of us haven't done anything silly/stupid in our lives (not kicking a cat!) all before the dreaded video camera.