In all honesty, we and Garry meant for superadmin to be the highest ranking access anyone would ever need.
In Gmod terms, superadmin default = root = superuser.
That's why Gmod allows it the most commands.
That's why we allow it the most commands.
In most cases, it would be best to create a lower group with less commands, which would also mean much typing but not as much as editing every allow for the superuser.
Until XGUI gets more completed, yes, you'd need to do alot of typing.
Remember though, this is SVN. It's under development... which means Megiddo may see this discussion and allow (or already has and it's just not clear yet something similiar to
ulx groupallow superadmin * !owner
Back up your groups and users files (which, when running SVN, you should anyway)
Try that.
Or, even try ulx groupallow superadmin "ulx" !owner
That in it's own right has issues though, won't be able to use asay to talk to the wall ops, etc.
Or if those two tries don't work, make one or two command access immunity changes like shown in the how to,
then go examine what edits were done to the data/ULib/groups.txt file, and copy those with a good text editor for the other commands you don't want performed on an owner.
Experiment.
Best way to learn.
Keep backups so you can recover from what you learned not to do.