Mr. Billy Hawkes:

I do not see why not. If I understand the question correctly, somebody who is a compulsive gambler, who wants to stop gambling and the temptation to engage in it, who essentially says, "Stop me from gambling", and who wants this to be known to all gambling sites, has given his or her consent. There is no issue from a data protection point of view, at least that I can see, in having such persons registered on a central database to which every operator would have access.