The new-gm tag is only for questions about being a new GM
I'm going to quote from the tagging usage on the tag's wiki:
Use this tag when the problem is inherently about being new to GMing, not just when the problem is caused by or the result of being new to GMing.
If the problem is about some other aspect of running roleplaying games, and being new to GMing is why you don't know the answer, don't use new-gm. Instead, use a tag that describes the problem you're experiencing. In particular, questions about how a game works should have the tag for that game system, and don't need this tag.
And of note here, we're talking about the question. Tags describe the question (which is not about being a new GM), not the answers (desired or obtained). The fact that the question got a frame challenge answer focusing on adding rules while a new GM does not relate to the question's tags.