Seems like despite the controversial phone call, the KTEB and KEWR controllers did what they were supposed to do for this guy, and then some.
KTEB could've just said "monitor Hudson CTAF, see ya" instead of handing him to KEWR for more advisories. It's important to remember that once you cross the riverbank there, if you are below 1100, you are in "Indian country"- completely uncontrolled airspace, with its own CTAF. To expect FF in there would be like expecting KEWR controllers to manage the pattern at Linden. He was no longer any controller's responsibilty, really, miles before that, as he exited the Class D, still below the Class B shelf. He was getting assitance beyond their required duties.
But he got the KEWR freq wrong, and apparently did not monitor the Hudson CTAF. Maybe he was still looking it up, who knows.
If you look at the video of the crash, especially individual frames, it seems there was a brief period where he could easily have seen the chopper low on his left (and vice-versa for the chopper pilot), but both pilots were probably already diverting their attention to the south (Piper's right, chopper's left/ forward), since that's where they both intended to go (the shopper was just getting established on that heading). Very easy to see how they could have missed each other.
And I don't care how disciplined you are- unless you fly that corridor on a regular basis, there's always a "gee whiz" moment as you enter, from wherever... it's hard not to halt your scan for a moment to take it all in (the sight of the city laid out beyond the river).
http://www.youtube.com/watch?v=cwT6yP1UXE4
IMHO, this was pilot error, on the part of one or both pilots... but even that can be forgiven. We all know how easy it is to not be looking where you "should" even if you are scanning diligently. Only takes a moment to go from a close call to a midair. So many midairs happen this way: one or both changing altitude and/or heading,and one or both moving into the other's blind spot just before impact.
I don't know if the Hudson CTAF would have helped, but it might have- that chopper pilot probably called his position and alt. as he turned. If the Piper pilot had been listening (although perhaps he was) that might have forced him to check low and ahead on both sides as he came over Hoboken
towards the river (which was the best time to see that helicopter).