Re: Explode is not interesting
I think most fuel-fired boilers, including coal, require a lengthy purge with forced air before they can be relit. The danger here is if the shutdown wasn't totally "clean" there may be an explosive fuel/air mixture hanging around in the firebox. I gather the risk of firebox explosion if ignition isn't even and immediate makes lighting large coal boilers kind of hair raising, not something you want to attempt every day.
On the whole I think the rapid connection/disconnection scheme might successfully produce an outage, although maybe only on part of the grid, depending on how alert operators were. (It's said the Northeast US Blackout of 2003 could have been stopped if grid operators had cut off part of Cleveland in the first hour or so of the failure cascade: https://en.wikipedia.org/wiki/Northeast_blackout_of_2003)
Biting the hand that feeds IT
