Usually electric connections get hot when there isn't a very good connection: All the current is forced through the small connection point heating it up.
I had a coworker with a bad charge cable on their EV with a similar problem. In his case the pins didn't fuse but the heat did melt the plastic of the plug on the car:
(The problem there was that the cable connector used wasn't rated for the 30A his car charged at. He still had to get the plug in the car replaced--twice! before he solved the problem)
Did they check the plug at the pedestal when they changed it?
I ask because usually the melting happens at the point of the problem, not 20' "downwind" of it (and I wouldn't put it past Thor to have something wrong there at the camper connector).
I also would suspect your surge suppressor didn't trip because this was probably a longer term event than it is setup to handle (surge suppressors are designed for that lightning hit, not a minutes long event).
Ah I can see that if the neutral line in the pedestal shorted to ground something like this could happen as your pin at the RV might have been the weakest link, however.