I know that, with Mojave, SIP has to remain unabled. The question is: what does it imply on the os behavior? A more particular question is: Does disabling SIP turn back our Mac OS a “more standard” Unix OS?
To my understanding it only prevents applications to have root accesses. If I am not mistaking, it is a completely OK thing in Linux distribution.
I know, that you are not an apple dev but I suppose, since you developped TotalFinder, you could give us some serious hints about everything SIP does.