For a start, it couldn't be sent to Nintendo as it would have to be made with homebrew SDK, so they couldn't release it. Secondly, there is no need for it to be a channel as it should only need run once. While if Nintendo were to go down this route, they'd need to make it a channel, as they have no other way of distributing code other than pressing discs, there is no need for this with homebrew. A simle DOL loadable via HBC would be fine.
However, I DO think its a good idea. If someone could find out exactly what Nintendo change in the save file to fix the issue, it should be "relatively" easy for someone to create a small save patcher which would fix the issue. Thanks to HW_AHBPROT, the save file can easily be accessed without any patched IOS, so it would just take a moderately skilled programmer to modify existing save game managers to use HW_AHBPROT, dump the specific save, patch it, and reinstall it. It should mainly be a case of putting together already existing code, and there are many devs in the scene more than competent enough to do the task.
Also, it should be noted that it is probably already possible to "fix" the glitch via homebrew by using Gecko OS to load the game with the walk through walls cheat, walk through the locked door and continue.