Only in Pprune can a rumour with absolutely no truth in it run to 17 replies! It didn't happen. To call the Apollo tragedy that involved the sad loss of Grissom, White and Chaffee a 'simulator' accident' is slightly insulting to their efforts and loss- this was a real launch pad 'simulation', not a 'simulator'. Whatever the article said, it was poorly written.
It never happened. Time to stop wasting space?