You're right, using a slippery slope argument is a type of logical fallacy, but for it to be a logical fallacy it has to preclude a result and also be implausible in it's steps.

My argument was did not preclude a result and was more a statement of fundamental change in the nature of law. If you change the application of laws from a definite system (the law applies to everyone) to a spectrum (the law applies to some people) then you are now on a slippery slope where as before you were not. As to the plausibility of the argument, we are literally seeing this effect in real time with Trump. Laws switched from being definite to being suggestions and now no one is truly certain what laws do apply and to who.