Apple SSD – How to Swap SSD Between Laptops

Fire. Unfortunately that would seem to be at odds with Amazon's return policy.

If Disk Utility can't see the drive, it's unlikely you'll be able to access it to overwrite anything (and overwriting on SSDs can be tricky in any event). Additionally, because the drive in the rMBP is a proprietary form factor, it's difficult to take it out and try to access it from another computer (which might not help any way). There may be adapters made in the future, but I'm not aware of any for sale at the moment.

The best preventative measure for this would be to employ some form of whole drive encryption, like Apple's FileVault. That way even if someone is able to read the data off the drive, it won't be useable unless they have your encryption password.

Apple recommends backing up your HD as they "can't guarantee the integrity of the data on hard drive." Or words to that effect.

Theoretically you can do what you have proposed. You may have boot issues, EG the Mac the SSD is swapped into may not boot but that is unlikely to damage either the Mac or the drive, so if you have the Mac and the time, go for it.

Personally I'd put the SSD in an external case, plug it and your backup drive into the same Mac and make a bootable image file of your SSD onto the backup drive. It's a little easier and you are less likely to damage more than one Mac accidentally by digging around in it... IMHO...