Anything grid tied is generally required to have phenomenally reliable shutdown if the grid goes down OR proven (and very expensive) automated switching that disconnects it from the grid if the grid goes down.
This is so those F150s are not backfeeding the wires while a repair crew is trying to fix it.
Ergo, if the local grid is "taken out", those F150s cannot be "on the local grid".
Article says "customers will allow their EVs to feed energy back to the grid – helping to balance it during peak demand". It doesn't say anything about what happens when the grid goes down during disasters
This is so those F150s are not backfeeding the wires while a repair crew is trying to fix it.
Ergo, if the local grid is "taken out", those F150s cannot be "on the local grid".