A locksmith may be able to open it with a Slim Jim. He might consider even asking the local police department if they can do the same. The PD around here has been known to help someone out with a Slim Jim now and then.
If he gets the door open I would advise trying to clean the latch assembly up a bit. These come from the factory with grease on them and over time that grease ages and hardens a bit and combined with dust over the years causes parts in the latch to bind a bit.
This may involve removing the door panel (once the door is open) to really clean the latch up. I’ve done them with aerosol carburetor cleaner followed by the application of a light duty aerosol grease. Hope that helps.