The basic "need" for this, as John stated above is that the 67-up center mounted POP-OPEN gas caps would do just that in a rear-end collision, they would pop-open, often dumping large amounts of gasoline out. Any genius can figure out why this safety-related item would come around for that reason alone...Add all the hype of the Pinto's blowing up back in the day and you have hysteria! NOTICE the engineering number and instructions date the design as 1993.
Sheese, the Crown Victoria was still blowing up well into the new mellinium if hit hard enough but that didn't slow down production of these hazzards much. You never saw a "Relocation Kit" provided by Ford for that tank (mounted behind the rear axle, these cars collapsed on 20MPH collisions even)
This item was intended to calm "fears" is all.