The threads don't get messed up just from cross threading. I've seen them plenty of times where they get dirty enough people start forcing them down and it eats up one of the threads. We know what happens when one thread gets ate up on aluminum and you keep forcing it.Don't see how the fnf would have been cross threaded since you don't have to put them together. It's probably just filthy.
As a heads up, if you get it cleaned and threading properly, that lower locking perch only needs to be hand tight. It should be easy to unlock with the car off the ground while using the tool. I see those get stuck when people tighten them really good and then set the car back down (which puts more force on that perch making it even tighter).
More than likely its like you and everyone else said. Just dirty and corroded, but no reason to cause more work or mess something up being careless.
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