There is nothing wrong with a question having a false premise. There is this aphorism that the most important word in science is not "eureka" but "that's weird", and it captures something very important: people are usually triggered to seek knowledge by noticing that the world doesn't conform to their internal ideas of how it should be.
Sometimes this kind of question annoys experts. It not only betrays that the asker is a beginner in this specific point, which means that there won't be a mentally stimulating discussion between peers, but more of an educational teacher-student interaction. It is also more work for the expert - he cannot simply describe what the reality is and pat himself on the back for work well done, he has to first engage with the student to help him unroot his false assumptions, and only then say what the right one is. This is much more difficult than lecturing.
However, "making experts happy" is not the goal of our site. It is the cheese in the mousetrap :) The goal is to help the beginners (and the perpetual intermediates) learn. And not only when it is not difficult to do so. Exterminating questions based on a false premise would prevent much learning, and accidentally also mean that a good chunk of our existing questions have to be closed.
Except for a few edge cases, I see nothing problematic with a question with a wrong premise. Such questions require a thoughtful answer which exposes the premise as wrong, explains what thought traps might lead into believing it, and corrects the wrong thinking. It might also arrive at a right answer, which makes it equivalent to the infamous XY problem. In some cases, it will not arrive at a right answer, because it doesn't exist, and that's OK. Even explaining why the answer doesn't exist is very useful for the learners (which is not only the OP, but the thousands of anonymous surfers who find the page).
The edge cases are those which deal with extremely common misconceptions, are very basic and need a thorough explanation starting with the basics, and crop up frequently. For those, we should create a canonical explanation and start closing the new ones as duplicates, without going into the finest details of the original question. This is how we deal now with a lot of the very basic food safety questions here, or how Biology deals with the "why didn't evolution create flyign pigs" sort of questions.
For the concrete question you linked as an example, I find your answer very good and useful. The OP obviously didn't know that there are liquors made without protein powder, and that knowledge seems to be quite relevant to his situation. So you helped him, and addressed the question. Sure, you did not say "yes" or "no", but in life, the answer to most yes or no questions is "it's complicated" anyway.