It's annoying to the hobby, but Wayne (personality aside) is dealing with copyright law as it applies in Australia, which is very similar to that in the UK. The basic concept as it applies in those places is that if you stop enforcing any rights that you have, then you also waive those rights. If he didn't go aggressively go after everybody that he became aware of, he would lose the rights he licensed from Williams. They also don't, as far as I know, have any kind of "Fair Use" type clauses like those that exist here in the USA. He's also got the ability to have Williams lawyers do his legwork, so it's not going to cost him squat to start playing whack-a-mole with websites whenever he gets bored.
I've bumped heads with this type of BS before when I was big into Warhammer 40k. Games Workshop is the same way, to the extent that they started shutting down all sorts of fan websites that exclusively catered to 40k subject matters (I.E. didn't have significant portions of other manufacturer hobby stuff on it.)
The only way we're going to get around this problem is if Williams declares the artwork to be public domain.... which is about as likely to happen as Megan Fox getting an Oscar for best actress. We're kinda stuck in this situation right now, which sucks.