Sure, the sensors collecting the altitude data might have been faulty, but the helicopter pilot was reportedly 50% higher than was allowed. You would think that an experienced helicopter pilot would be able to gauge that they were a full 50% above the allowed limit. From the reported information, I'm not sure there is reason to believe that it was much more complicated than altitude misjudgement on the part of the helicopter pilot, unless they were somehow unaware of the allowed limits in that airspace.
If something was caused by pilot error, there's nothing you can really do except shrug and hope it doesn't happen again. It's an intuitively appealing explanation, and usually wrong. The aviation community has spent decades rejecting that instinct and looking for contributing factors that can be addressed. Those other factors are almost always present, and improvements can then be made. The net result of this process is that aviation has become incredibly safe, which would not have happened if people were content to say "eh, it was probably pilot error."
