I know that LaTeX is not a part of linguistics, but I'm sure many people do use LaTeX to write up papers on linguistics and it is a useful tool (see this Answer where I created a Vowel Trapezoid). There is a specific Tex.se, but I find that a little bit of linguistic expertise could be useful there.
If a specific question treats about Linguistics and Latex, well, why not tag with it? No problem as long as it's relevant (and the question is not only about Latex, and in that case it would belong to Tex SE).
Note however that that question should not be tagged with latex since the question is not about Latex and we tag questions not answers. You did provide a solution with Latex but the question was asking for a picture basically and it could have been provided in several ways.