From the pictures I saw...it looked like the incident yesterday happened with the "older" cars. The accident in October was with the "newer" cars, but engine 504 was pulling both trains when these rare occurrences happened. Not sure if there's any correlation there, just an observation.
In my opinion, the incident yesterday, even though a car "derailed" is no different than something happening with a roller coaster that has a mechanical issue and stops at the top of a lift hill and people have to evacuate. A ride had an issue which enacted safety systems to prevent disaster. Now, there is a huge difference in a roller coaster derailing and a train, but my point is that the safety systems that had been implemented worked and no one was hurt. Yes, it says one person was, but if you decline first aid, you're not really hurt. Although it is scary and when you hear "derailment" you fear the worst, whether that's an Amtrak train or the FSDL, but IMO SDC's new safety systems, that were recommended by the state of Missouri, worked and did their job. It shouldn't prevent you from ever riding it again, if that's how you fell, but to each their own.
I would raise the question as to when the park just replaces the track of the entire layout. I know that takes time, money, etc...but maybe that's the next conclusion...idk, I'm not an expert, just a loving fan of the FSDL that wants to see it run another 60 years without injury, fear and bad PR, just like before.