In fairness, the decompiler didn't work on the protection method :)

I think that both halves of the author's thesis are true: I bet that you could use this device in a more complicated way, but I also bet that the authors of the program deemed this sufficient. I've reversed a lot of software (both professionally and not) from that era and I'd say at least 90% of it really is "that easy," so there's nothing you're missing!