Then that still begs the question, why would a nutjob be trying to find you? Furthermore, the nutjobs we're talking about aren't out to "find" any particular person, they're looking to "find" people who fit certain criteria.
A serial killer might target white women in their mid-30s, of which there are an exceedingly large number. Fact of the matter is he doesn't have to set up a website or look online to find people meeting his criteria.
A thief, as I already mentioned, is looking for people who appear to be relatively wealthy, amongst other criteria. You cannot determine this from their MAC Address. Google Street View? You can infer somewhat based on their house and vehicle, but you still have to fit those other criteria.
A mugger wants someone who just walked away from an ATM.
The one thing, the one important pattern which you should be noticing is that the criteria do not include "Full Name" or "Street Address." Sure, identity thieves need those tidbits, but they also need a lot more information that's much more difficult to get.
but some loony decides to make it readily available
Exactly. Some loony. We cannot legislate to the loonies, because if we did we would have no freedoms left.
Who knows what the consequences might be!
Exactly. You apparently don't. I will give you a hint: the consequences will be the exact same whether the information is available or not. A nutjob A) doesn't care about who, only what and B) isn't going to stop just because it's difficult to find his target.
There have also been cases of would-be Muslim terrorists looking for any soldier to kill
I'm sure. There's a whole ton of soldiers AND would-be Muslim terrorists in Afghanistan and Iraq playing this little game out as we speak. I'm sure the soldiers would love it if someone told them the location of every Terrorist, and I'm sure the Terrorists would love to know the same about the soldiers. Wanna know what's funny, though? Neither group stops, even though they don't have that info!
I'm going to go through the key points of the Data Protection Act according to Wikipedia as a nutjob. Just for posterity's sake.
Data may only be used for the specific purposes for which it was collected.
Okay. I will not do anything besides murder the person whom I'm targeting.
Data must not be disclosed to other parties without the consent of the individual whom it is about...It is an offence for Other Parties to obtain this personal data without authorisation
Okay. I will not tell the police what information I have on you.
Individuals have a right of access to the information held about them...
Okay. If you want to know what I know about you, I will tell you.
Personal information may be kept for no longer than is necessary and must be kept up to date
Okay, I will discard the information immediately after the murder, and in the meantime keep tabs on you so I know the information is accurate.
Personal information may not be sent outside the European Economic Area...
Okay, I will not send your information to my friends outside of Europe.
Subject to some exceptions for organisations that only do very simple processing, and for domestic use, all entities that process personal information must register with the Information Commissioner's Office
Murder is an exceedingly simple process.
Entities holding personal information are required to have adequate security measures in place...
I will never maintain a hard copy of your personal information.
Subjects have the right to have factually incorrect information corrected
Alright, if I have the wrong address and you want to make sure I have the right one, please do tell me.
The Data Protection Act doesn't afford you the protection you allege that it does. It regulates what an organization does with personally identifiable information it collects.
I have the right to collect information from you at any point in time which you may enter into business with me. This includes if you visit my website. If I happen to pull your MAC address and use it for the purposes of geolocation, I have every right to do so. I may not share your information without your permission, but I can collect my own, because you visited my website.
Note, of course, that a MAC Address cannot be personally identifiable, even though it's unique, as numerous individuals may be using the same router. The same goes for a Geolocation: it points to longitude/latitude coordinates, which can in some cases be translated into a street address, but any street address may house any number of individuals, and you cannot possibly determine which person based purely on those coordinates or street address.