Co worker of mine lives in PA and is flying out of Newark airport.  He is going to fly out with his ar15 to use at his destination.  Of course since he lives in a free state it has a threaded barrel, flash hider, bayo lug, and a collapsible stock.

I told him he’s nuts and to send it to a ffl and pick it up when he gets there or should have got a flight out of Philly.

He said he called TSA and they said no big deal.  What’s the odds he is going to make it through and home with no problem assuming no traffic stops on the way there or back?

I agree with you - he's nuts.  While the NJSP web page claims to honor FOPA, it's just too tempting to a LEO to get a 2nd degree assault firearm possession charge on someone.  FOPA may eventually lead to his exoneration, but it won't be without significant cost.

Couple that with the 3rd circuit's ruling that FOPA only applies when the firearm is transported "in" a vehicle, and therefore does NOT apply to someone walking from a parking lot to a terminal, and your friend is setting himself up for a really bad day.

No, No, No! Tell him no. Any non compliant Ar-15 that they find will get him a one way trip to jail.

In all seriousness have your friend ship to an FFL from PA to another FFL in free state. Worth the cost instead of rolling the dice in NJ.

Update.  He said he changed his flight to fly out of Philly.  I think it was a smart move on his part.

Best decision he's ever made, most likely.  Now just tell him to hope they don't get diverted to EWR on the return trip  

In all seriousness, IF that were to happen (and it's happened before, to a guy from Utah), make sure he knows to refuse to take possession of his luggage.  If the airline is putting him back on another flight to Philly, they keep the baggage.  If they're busing him home, THEY LOAD THE BAGGAGE ON THE BUS.  If they're putting him up at a hotel for the night, again, THEY KEEP THE LUGGAGE.  He is never to have possession of that firearm while standing on NJ soil.

I highly doubt you would of had a problem I fly once a yearto Texas  to go hunting with my rifles and from experience
1.  tsa doesn't know what they are looking at
2. Tsa is only checking for explosives and to make sure it's not loaded.

Your in a room with the officers the whole time

You are correct but the concern at least from my perspective is that he will not have a NJ compliant firearm while in NJ. Would not want to deal with an overzealous TSA agent or LEO while in NJ.