One way to deal with this is to set the temperature to the maximum temperature you want the butt to reach if you are called away. So if you planned to pull the butt at 195; set the temperature to 195 or 200. The butt can never get hotter than the oven due to thermodynamics, so if you set the oven to the maximum temperature you want the butt to reach you will be OK. It will take longer to cook at the lower temperature though; as the butt approaches the final temperature the rate of temperature rise will slow as well.
If you have been contemplating an overnight cook but are worried about the butt being done before you wake up, this technique works the same there. Just set the temperature to 195 and go to sleep. In the morning crank it up to 225 or 250.
On the other hand, it is hard to overcook pulled pork, even at 225F. - Duffey