No, it was not under warranty. They said they were unable (unwilling?) to order parts to fix.Was it under warranty? Because I guarantee that any Lexus dealer didn't do this and leave the vehicle unrepaired without ordering the parts, and that being only temporary. Actually it's illegal, and if it wasn't under warranty they wouldn't simply state it was unfixable, they would offer to order the motor at cost to you, if not replace the entire door.
The car was 13 years old, so it is conceivable that parts were hard to come by. But the 3rd party shop I went to next had no problem fixing it for less than the Lexus shop charged me to say they couldn't fix it.