Questions must be judged for fitness to Mi Yodeya on their own merits, not on those of answers that have been posted to them. My standing proposal for how to evaluate the topicality of questions of this nature is given in my answer to The Parameters of "Jewish Life" Scope, which you linked here:
I believe that the guiding principles (though not a bright-line rules) for on-topicness should be:
Is this question expressly or implicitly motivated by a desire to understand or practice Judaism?
Is it reasonable to expect that a group of people who base their lives on Judaism would be especially able to give informed answers, due to their basing their lives on Judaism?
In the example you posed , the question clearly passes both tests:
The question is motivated by the author's desire to furnish his shul for the purpose of practicing Judaism.
It is reasonable to expect Judaism experts to be especially able to give informed answers, based on their familiarity with the function of the shulchan in a shul and (in the case of the subclass of Judaism experts who are shul-furnishing experts) how to build one.
The answer, on the other hand, is pretty clearly not a strong answer, as reflected in the comments. A strong answer to that question would definitely employ specific Judaism expertise regarding the form and function of shulchans. Given that the question is asking for dimensions, and this answer offers a suggestion for how to determine dimensions, I suppose it provides enough movement toward an answer to not be deletable, but others, including me considering it again, may disagree. In any case, the presence of a weak answer like this doesn't impugn the fitness of the question.