I think you've figured it out by now, it's a scam. I had a shotgun listed on armslist once and as always stated "face to face only". A guy responded by email, and later by phone begging me to ship it to his FFL. He eventually texted me photos of his DL, hunting license, and even his hunting dog! Eventually I gave in after he offered to send a USPS money order and I cashed it at the local post office. I even called the FFL and verified they had been hunting partners for decades. All went well and I eventually had a good laugh over how bad he wanted that old Browning 20 ga.
Would I ever do it again, probably not.
Would I ever do it again, probably not.