Interesting. If we can assume the experimenter's failure to enforce the rules was mere clumsiness or incompetence, rather than an indicator of underlying intentional manipulation of the experimental conditions à la Stanford prison experiment, this can be interpreted in many different ways.

The (eventually) disobedient subjects were better at respecting the experimental process they were given than the "obedient" ones who went all the way to the maximum voltage. Why was that?

Could it be a sign that the disobedient subjects were on average more concentrated on the task at hand (smarter? less stressed? better educated? more conscientious?) than the ultimately obedient ones, and therefore were more likely to realise they were "hurting" the alleged learner and stop?

Or could it be that the obedient subjects were more likely to realise there was something fishy going on, suspecting the "learner" wasn't really being shocked, and thus were paying less attention to the learning rules?

Or was it, as the article suggests, that the obedient ones may have shut down emotionally under pressure to follow through, and their mistakes are the result of that?

Or were the obedient ones more likely to be actual sadists, who were enjoying the shocks so much that they didn't even care if the "learner" didn't hear their question, giving them a greater chance of shocking them again?

Unfortunately I think the Milgram experiment has become so entrenched in popular culture that there's absolutely no way it can be properly repeated to explore these questions.