The article suggests, though, that other compact cars had a similar bumper and fuel tank design, including sharp objects near the tank. The issue wasn't unique or exceptional. The one cherry-picked metric that came out of it was that the Pinto experienced puncture for rear end collisions at a marginally lower speed than other cars, and, after regulations were put in place to increase that minimum, fatality rates were not affected at all.
Any fatality effect is noise compared to the other causal factors in fatal accidents: highway design, speed, weight of the objects of collision, level of alcohol intoxication. And even factors within Ford's control trumped the Pinto gas tank design in importance. It's just that one particularly grisly and tragic death makes for some really bad PR.
Disclaimer: I've got no knowledge of the Pinto case besides hearsay and what's in this article.