I made the changes you requested. Building the package with gssapi support was the whole point of the pull request, the build option was added because @xtraeme requested it. So adding it just not to use it would be useless from my point of view. I see no harm in building cups with gssapi support, it is done this way by many distributions and is apparently now considered to be the default by upstream.
But I agree that the most important thing is to get cups working again so I don't want to argue to much about that. I've ammended the PR again to remove the option as default and pull in a patch taken from alpine to the cupsd.conf which removes the need to have the package built with gssapi enabled to start the daemon.