BBC Purchase Botnet from Hackers, It is illegal, Unethical or OK?

BBC's technology program "Click" purchased a botnet recently as part of an experiment meant to show how botnets can do damage. But by putting money in the hands of hackers, did BBC's program do more harm than good?

Sources:
http://www.eweek.com/c/a/Security/BBC-Program-Purchases-Botnet-Touches-off-Ethical-Debate-859181/

http://www.informationweek.com/blog/main/archives/2009/03/bbc_botnet_expe.html