I'm going to move someone else's laundry that they left sitting in the machine.
Could you not wait for them to move their own laundry?
I felt like they should have moved it already.
I get being frustrated when you need to wash your clothes and someone left their clothes sitting in the machine. Try finding them and letting them know their clothes are done and that you need to start your own load. If you just move them they'll be upset to find their clothes in a wrinkled pile.
I'm doing it anyway.
It is not polite to do something that you know will cause someone else to be upset. If it's really an emergency and you don't have time to find the other person, you should leave a note explaining the situation. Otherwise, you can just wait or try and find the person.