Third party "transfers" happen thousands of times every day.......it is called UPS and FED X. It just has to go to a FFL to be transferred if across state lines. I am going to do exactly that with a member from Oregon in the next couple of days. If he was from Idaho, it wouldn't be required but the Fed gets involved across state lines.I wouldn't worry about any ambiguous laws that the seller may or may not be bending. If you go to a FFL, fill out a 4473 and buy a gun, you are insulated.
The only issue for the seller, is that the third party is technically being transferred a gun ,not for him, so it could be theoretically considered a straw purchase.
If you are really worried, have it shipped.