That's a great question. Porsche has always closely guarded their Brand and IP. Generally they do not license anything except for branded merchandise. They even copywrited their Porsche font.
Checkpoint only has drawn images of the cars on the machine. There are no crests, names, logos, model numbers, or anything that says Porsche on the machine or in the literature. So there is something weird about the 'licensing' here.
Around 89-90 was a low point in Porsche's existence. They were transitioning manufacturing, design, leadership and dealing with the remnants of a world wide recession and currency fluctuations that killed their sales. At the time they were selling about 30% of the volumes throughout the 80s.
Maybe Data East lawyers thought they could sneak this by? Or there was a weak link in the marketing team that allowed the license, I'd love to know the real story.
I am a Porsche collector and really wanted this machine when I got into the hobby. Its too bad the pin was a one shot wonder, as it didn't stay very long.