Regarding why he ignores the ruling, the article says he does it on "principle". Presumably, he feels it's his land and he can do whatever he wants with it. But it would be interesting to hear him defend his position himself rather than having to put words in his mouth.
As to why he gets away with it, presumably the penalties for ignoring the courts are not severe enough. Maybe he's just rich enough to pay whatever fine has been levied on him and keep access closed.
It reminds me of when Microsoft was fined by the courts something like a million dollars a day for violating antitrust regulations, and they just paid and kept violating (if I'm remembering this right). Some companies prefer to just get the law changed in their favor instead, or maybe get people elected who will defund regulating bodies or put their cronies in control, etc. When you're rich enough you have many options for evading the law.