I think you’re right.
Without looking at the code, I think it’s 1-4 hours of work, maybe more of it included proper tests. It would be much faster to hard code the group(s) in question…
There’s a thing called guardian that I think is what you’d need to modify.
But, it would probably help if you back up and describe what you really want to happen. In what contexts do you care for people to be able to see the group? Why?