It's unenforceable and ridiculous as a practical matter.
How enforceable it is I think comes down to how competent and attentive the probation department is.
Sure, you can argue it's dumb because Nick could just sneak off to a hotel with April when nobody is looking, but you could also say Nick might be able to break any other condition of his probation when nobody is looking.
Of course it's enforceable because at this point the only competence needed from the probation officer would be creating a 24/7 tip hotline along the lines of "1-800-NOFUN4U" and posting it on the Farms, after which Nick gallivanting around with April would somehow be caught within a matter of weeks. Even if they convince themselves they're being careful with quieter social media, let's not forget that it took things outside their control that were so obscure as a
tattoo artist's separate social media and
distant background of a WCCO news video to pin down how many of the throuple accompanied April at a tattoo festival, to say nothing of an underestimated vast wellspring of haters in the local community who could again stumble upon them
stopping by the Dairy Queen, or
picking up a za at Zorbaz, or
stuck in line at the Spectrum store, etc. Hell, even if they convince themselves that surreptitious trysts in hotels will be safe enough, then they had damned well better stick to hotels with underground parking or take a bus, because even traffic tickets ITT have made the make, model, plate number, and VIN of each of their vehicles simple enough for any random KF lurker, Toe fan, Herren fan, or Scandi prude among their fellow hotel guests to stumble upon in the parking lot and call in.
Face it, Nick: if you thought you had to look over your shoulder for the "Activity Police" before, that pales in comparison to the paranoia that will come with knowing that one brief coom session with sidepiece after January means another stay in the slammer. There is no backroad route remote enough, no hotel registration alias generic enough, no disguise cunning enough to stop the Activity Police™ from ruining your fun. Nothing is beyond our reach.