The system that shut itself down poisoned the standby through replayed commands
"Why the design philosophy was automatically to replay commands on SFS failure; whilst this is appropriate in some circumstances, on this occasion, repeating the command to enter Watching Mode led to the double failure of the SFS."
As I see it it was these journalled commands that caused the trigger to be repeated on the second system, bringing that down. Presumably if the first system had given notification of the reason why it was shutting down then the list of commands to be journalled through could have been inspected prior to replaying them in order to find out why failover occurred, thus sparing the second system from a similar fate.
It seems that this opportunity was not taken, presumably as time is of the essence in replaying commands otherwise they may no longer be relevant. A flaw with systems such as this is for a human being to have to make a very quick decision as to whether the shutdown has occurred for hardware reasons, or if it is software, or what. The report that might have been served up by the shut down process may have indicated a fault that sounded hardware related, and therefore a decision was taken to let the journal run through without any breakpoints set.