The abstract-algebra tag is a very general tag which is generally relevant for questions regarding groups, rings, fields, modules, and vector spaces. These kinds of questions tend to pop up in advanced undergraduate or elementary graduate level courses. The question being considered here is about algebraic geometry which is a much more specialized field. The question was appropriately tagged with algebraic-geometry.
For comparison, this is somewhat analogous to the distinction between the analysis tag and the hausdorff-measure tag. Questions involving the Hausdorff measure are likely questions about analysis, but the Hausdorff measure is a more specific tag, and questions about the Hausdorff measure may not be relevant to the folk who follow the analysis tag.
In short, I think that the reviewers made the right decision.
As an aside, suggesting an edit after it has already been rejected is inappropriate. In the future, if you feel that a review is mistaken, please raise the issue on meta or in chat (either Tagging or CRUDE might be a good place to look for help).