Interesting technical issue (though generalized):  The distant out-of-town radiator shop where I dropped off my leaking 70 yr. old original for repair, told me I couldn’t leave it for 3 months (only there that often, and won’t need to return sooner since I’m installing an aluminum one for now).  They said the alkaline air (!?) would cause the braising to corrode away!  My first thought was that they were B.S.ing me because they just didn’t want it in their way that long, but then there was some talk of maybe storing it full of antifreeze. Did new brass radiators have a shelf life? Or only ones that get repaired maybe?  I noticed the ‘stored full’ talk only came up after I made it abundantly clear I wouldn’t make the long drive any sooner.  B.S. or not?

6 VOLTS/POS. GRD. NW INDIANA

I don't blame the shop for not wanting to store your radiator for three months; they're not in the storage business. As far as shelf life? I bought a new US Radiator several years ago that's still in the box; there are no visible signs of deterioration. My original 55 radiator was removed years ago and stored dry in my garage, not in a box. I can't see any difference. 

Why would a radiator be less susceptible to "alkaline air" corrosion when installed? Makes no sense. 

I could see where a small shop might be pressed for storage space, but this was a huge, modern, big-box-like operation. Sometimes, holding products for long delayed delivery is an expected part of ‘business-as-usual’.
The only logic I could imagine re: ‘susceptibility to air exposure’, would be that the needed repair (braising) was in the lower tank (which is always flooded when installed), and maybe the material used for repairs is very different than what is used for manufacture (if so, then I must remember to warn them not to drain it before pickup).

6 VOLTS/POS. GRD. NW INDIANA