You could do it by having a value that can be set
globally that all GmScripts can access and turn it on and off, and then
check it in each script to see if that script should execute or not.
The problem is, I think they STILL have not allowed some common global
variable space, which some people have been asking for, literally, for
years. Unless they have added it and I missed it.
There might be some other way now to do it. I haven't kept up with many
of the new changes, like the library includes and some other stuff like
that. You will probably have to get creative, if it can even be done at
all. (you can always modify the add on itself, which I have done from
time to time over the years so that I could do stuff that others either
thought shouldn't be done, or no one wanted to add to the code)
Some will scream "security risk!", but that is only the case if you
don't know about it, and care. There are personal things I do in my
scripts that I don't publish for the world to see, that I wouldn't,
necessarily, do in a script published for the world. Which allows it a
certain amount of inherent security. Plus, even if someone did somehow
try to mess with me, I would notice it, and do something to fix it, if
I could. But the chances of that happening are pretty much zero.
In your case, who cares if you want to have some "global value" that
some of your scripts check to see if they should execute, or not. As
long as your scripts aren't accessing nuclear energy websites that can
turn valves off and on, etc. And you are aware of the other scripts you
are using, which wouldn't mess with your global value, anyway.
The "problem" with @include and @exclude, is that they are static and
you cannot modify them programmatically, so I don't think they would
work for what it sounds like you want to do.