That is a heartbreaker of a break. Anything can be fixed, including that. Since it's broken almost square there is not much long grain-to-long grain wood surface for epoxy to give a strong bond to. What will be needed is a solid rod down the middle inside the wrist to provide strength and for glue to bond to. (1/2" or bigger diameter carbon fiber, fiberglass, etc.) Unfortunately with a break like that which goes cross-grain there is no way you will totally camouflage the break line after all is said and done, but it can be made solid enough for shooting and hunting.
Therein lies why it's so important to consider grain flow when selecting wood for a stock. Pretty/highly figured grain doesn't belong in the wrist, it's just asking for trouble down the road. (Not knowing what happened in shipping, and not knowing how well the rifle was packaged, I can't guess as to what could have been done to better protect it. It's why I'm anal about over-packaging guns for shipping- the wooden reinforcements I put into the box ahead of the gun and packing materials add greatly to the bulk and final weight of the package, and drives the cost up dramatically, but at least I never sent a gun that arrived broken. I have received guns broken due to slipshod packaging though. One was a pre-war custom Krag broken exactly like this M54 was- the idiot merely dropped it in an empty box, taped it up, and consigned it to UPS.)
I also always dismantle the rifle and position the barreled action to act as a further stiffener for the wood stock. A PIA maybe for the recipient to have to re-assemble it, but it does make for a stronger and smaller package better designed to withstand the ravages of modern shipping practices. A friend who did a career with UPS advised me that a package really needs to be able to withstand hundreds of pounds of pressure or safe arrival is a crapshoot. Imagine your package being at the bottom of a load of boxes stacked in a tractor trailer, put (thrown) there by a bunch of horny-handed hourly guys working against the clock.
The rifle was well packaged, the only way it could have been better packaged would have been if it had been in a gun case. It is a bummer for sure, but like my FFL said, better have it break in shipping than while shooting. It is in good hands with Dennis Erhardt. You're right though, it is a great example of why grain layout in the wrist is so important. I received a Pre WWI Mauser Type B recently and the box it came in was trashed, rifle was fine though.
