The SLIPPERY SLOPE argument is nearly always rhetorical nonsense.
But it cam be used in BOTH directions/
IF we fail to allow same sex marriages then the next step on that slippery slope is not allowing marriages of people of different ages, races. , cultures etc etc etc.
The slipper slope argument is always a false argument EXCEPT in the case of people walking on SLIPPERY SLOPES.
duh!
Hohum, the slippery slope argument is only a fallacy if no driving cause is given.
Example, if I say that loaning more money to a drunk to get booze is a moral hazard because he will simply buy more booze, get more drunk and need more money, it is in the form of a slippery slope argument. But it WORKS because there is a driving mechanism, the alcoholism.
But if I said don't lend money to Fred because he didn't pay me back last year and he wont pay you back either and that debt means more likelihood of default on loans, etc, that is a false slippery slope and a few other fallacies as well.
Whether there is a driving mechanism is the key and in the case of the consummate nature of inurement to sexual satisfaction achieved by strong sensational and/or debasing behavior has such a mechanism, as inurement causes a person to crave ever stronger and more debasing experiences.
In regard to this case, the loosening of standards, it is something anyone with much experience in the real world can experience themselves. once standards start to slide, whatever the causes of them to start, they do tend to continue that momentum unless some outside factor acts to stop it.