Brd709 The Dine Out restaurants are owned by the household, not an individual sim. So, when you move a sim out of the household, the ownership of the restaurant stays with the household, not the sim moving out. Same thing happens with vet clinics and GTW owned businesses. According to the trailer and other info released for the upcoming Business and Hobbies expansion pack, the new venue type added will allow businesses to be owned by individual sims. Idk for sure, but I doubt that there will be many, if any, changes made for the existing business using the earlier business type venues and they will continue to work the way they do now. We'll just have to wait and see what we can do when the pack comes out.
As to what you had happen, you might be able to fix the ownership by moving the sim who is supposed to own the restaurant back to the household you moved them out of, then move the other sims out. Then move the owning sim to where you want them to live and then move the others back if you want them on the original lot. Lot of moving to do that and you'll have to remember to dump the contents of chests, the fridge, flower and jewelry workstations and any collectibles and personal items into the sim's inventory so you don't lose them or the collections when you move the sims around.
Hope this helps.