I suspect the real problem is that someone plugs in a device via HDMI, switches the input to that HDMI port, watches a movie, does some work on their laptop, etc, and then doesn't change the input back to the default hotel tv input. The next guest checks in and can't figure out how to change the input then calls and complains. They are just trying to avoid going to dozens of rooms everyday just to change inputs.
Instead of a obviously false and misleading sign, they should just have the housekeepers make sure the tv is on the right input when they clean the room between guests.
The most basic setting in a tv's "hotel mode" is what input/channel to set at each power cycle.