This is exactly why the 2014 wording was good, and the 2024 wording ruined the spell. I agree it's unreasonable to order the sidekick to simply leave, but a very cleverly worded suggestion can do the same thing. For example: "Hike to the nearest villiage and tell them we're under attack!" That accomplishes basically the same thing as "Leave and don't return," right? But as a DM, I'd be forced to accept that. And I'd accept it with a big smile, because I love it when my players are creative.
Yes, that's still too powerful for a second-level spell, but at least in that case we're rewarding the ingenuity of the player. Giving an outrageously powerful benefit as an award for great play seems fine to me. Remove the requirement for great play, or honestly even good play, and now it's just unbalanced.