Ooohhh! This will be interesting from a reverse engineering perspective. Also, does that mean I can get iMessage on PC?
I assume you could just buy some $10 iphone 3gs to grab a number from.
I imagine this will be extended in the future so that they can begin to clamp down.
Can you access iMessage just through the Messages app on Mac?
Otherwise this could cause issues with a real owner or the Hackintosh community, and is just acting in bad faith.
Who is harming the purchasers? Apple, or the hacker copying down a publicly available piece of information?
Serial numbers are generally used to corroborate ownership of an item in legal scenarios (and may count as a conditional representation of PII).
Apple uses them as unique identifiers to authenticate their devices and tell them apart, and very presumably protect against various forms of fraud.
Where SecureROM is up there in terms of being buried pretty deeply in the SoC, I imagine the serial number is on a similar level in terms of not being modifiable/forgeable. So the "device <-> serial number" relationship is pretty indelible, you can't change it. And given that the way the relationship works is that you buy the hardware and then it becomes your property, you also effectively "own" that serial number to a relatively concrete extent. Thus, I can see slapping a theft charge on someone who runs off with the serial number of a device they did not own.
There's probably a much more concise way to wrap up the "nope" - the above points are somewhat general - but TL;DR, I really don't think that would work.
This might get you in trouble though, less about the theoretical element of fraud and more that they’ll legitimately believe the device has been stolen.