I posted the same thread a few weeks ago. You can definitely edit the image yourself and/or replace it with a different one. It was never clarified as to whether it is ok or not to distribute an edited one.
Bethesda has clearly stated that no permission is given to redistribute modified versions of the game executables. You do however have permission to distribute a patch that the end-user would run to modify the exe. The reasoning here is that distributing the game executable in any usable form would be giving away the game for free, undermining Bethesda's business interests - but a patch would require the end-user to have purchased and installed a legitimate copy of the game for the patch to modify. The Morrowind Code Patch is a prime example.
It's true that some people may have acquired copies of Morrowind through unprofitable means, but distributing a modified version of the game executable takes away all doubt that Bethesda nets a big fat zero. :down:
[edit] not to mention the confusion that could be introduced where someone acquires the exe expecting it to be the original and it turns out to be modified, causing issues with future 3rd party patchers that expect the exe to be the original. If the end-user has to apply the patch themselves, then they know what they're getting.