I think the point that many are missing is that is not known for certain that an engineer is more likely to enjoy certain hobbies over others. People use their personal experience to develop a heuristic which this test is designed to reveal.
Getting hung up over the specificity of the hobbies and interests and the likelihood of those hobbies and interests representing either or a lawyer or an engineer is irrelevant, because the only factual data that was provided by the questioner is that 30% of the participants were engineers, and 70% were lawyers.
It's not "getting hung up" about the specifics. They are relevant, and clearly deliberately chosen. You're right that we don't know this likelihood with absolute 100% certainty, but that doesn't mean we should dismiss our personal experience, and a bit of logic (maths is typically more useful for, and a more practical path into, engineering than law, and there's far more politicians in my country with a background in law than there are with a background in engineering) out of hand.
What this article is trying to present is heuristic errors - like question 1, where ignoring of the fact that sample size is relevant gets you to the wrong answer. Ignoring the likelihood that there is a correlation between personal interests and career choice seems to me to be the equivalent heuristic error for this question.
Let me give you an alternate example. There are roughly 700 million Europeans and roughly 300 million Americans. If I randomly picked one person out from this, gave you no other information and asked you where they came from, you'd have a 70% chance of guessing correctly by saying "Europe". If I told you that their first language was English, that they loved American football and baseball and hated soccer, and that their favourite TV show was Conan, and then asked you to guess where they came from, it would be hugely naive to ignore that information and still assume that they were probably European. Yes, it's entirely possible that there are Europeans who fall into all of those things, and I've not done a survey to find the exact percentage of each group that answer this description, but I'd be prepared to put a fair amount of money on the fact that there's a larger overall number of Americans who answer it than Europeans, so the smart guess would now be that they are American.
Getting hung up over the specificity of the hobbies and interests and the likelihood of those hobbies and interests representing either or a lawyer or an engineer is irrelevant, because the only factual data that was provided by the questioner is that 30% of the participants were engineers, and 70% were lawyers.