Lynx, IsSuperadmin has nothing to do with ULX.
God power to your server when IsSuperAdmin is true whether ULib is installed or not.
Deny command access to your groups that inherit superadmin if you don't want them to have ulx commands.
Which, really seems like bad design. superadmin should still be highest. "Head admin"

?
Why can't superadmin be highest? r00t.
Garry's Gmod, in all the design challenges we've had to work around over the years, is the foremost reason superadmin is highest group for ULib.
It's the highest group according to Gmod. Without ULib installed, or any other access control, superadmin is still the highest group.
We only added "operator" as a custom group as an example.
Owner, well, I'm not going into the rant I have towards a particular gamemode and it's developer(s) decision to deviate from the norm.
i cringe everytime I see someone using a particular gamemode that apparently provides instructions telling them to make themselves owner.
If Gmod itself understood what the heck owner was, it might be ok. It doesn't. Gmod and 99% of the non-gamemode based scripts will likely have no clue what owner is.
Even the Gmod wiki says, paraphrased, "make yourself superadmin if you're hosting a server"
Aaron, I didn't look at any of those links referenced, but presume every single one of them was due to confusion of someone using that gamemode I hate supporting.
IsSuperadmin will work if any group inherits "superadmin".
If someone doesn't understand inheritance, we have several FAQs and a nice community to support it.
I understand the why of your idea, I just am totally against it.
As stated by others, it goes against default Gmod, while we tried to not break it and still allow isadmin and issuperadmin to work.