Go back and look at the VF incident.
I forget if it was car 4 or 5 in the train, but the fin on that car impacted the brake caliper and derailed the car behind it.
With magnetic brake fins, the impact could warp the fin further without shearing off, jamming the train in place. For this, look at the pics of Xcelerator.
Regardless, this happened in an area without trims, and therefore, is not what occured.
When you're talking about mechanical / structural failures, issues are almost never black+white.
In the end, I'll just wait to read the accident report, as all this speculation is just that: Speculation.