John Honovich can slay a 20 foot tall man! Can anyone prove me wrong??? :)
My best answer would be, "No they do not. Nor does any camera manufacturer ever make this claim, because they've never been tested in their cameras, as 2TB SDXC cards do not exist - it is a theoretical limitation based on currently available storage technology (bits per sq in)."
SATA drives (currently capped at about 4TB/disk) have a theoretical limit too - between 50 and 60TB. The theoretical size limitations have increased because they changed the way they are able to store bits on the platters. The same thing could, and probably will, happen with SD technology. They've already been able to overcome some earlier Flash limitations to make them more viable - I imagine they will find other cool new ways to make them bigger, stronger and faster. But the 'new' ways might not be seen/recognized the same way by the camera - who knows?
Back to SATA for a minute:
Embedded devices that use SATA drives will 'certify' a drive size (per bay and/or in total) is 'compatible' with their devices that is lower than other available sizes because they have tested it and it works - while they maybe haven't tested the (newer) larger drives. Will the larger drives work? Probably. But who knows what's in the firmware that might need to be tweaked to accept a larger volume than was originally tested? By the time the larger drives come out, they may be different 'enough' to kill the firmware integration compatibility that exists with the currently tested drives.
I guess that makes me one of the good guys too? :)