Rather confusingly, the description that somebody asking a question is given of "Policy and Style" is slightly different to the description on the help page.
From the help page: "This category is for questions about the finer points of WikiTreeing. Ask for help on the hard decisions or discuss WikiTree's policies, procedures, standards, categorization, collaboration methods, etc.". That implies to me that one of its uses is for discussing categorization, so as you say it is a reasonable place to request a new category.
From the page you get when you ask a question: "The Policy and Style category is for the finer points of WikiTreeing. Ask for help on the hard decisions about implementing WikiTree's policies, procedures, standards, categorization, collaboration methods, etc." That implies to me that it is only for hard decisions, about categorization or other topics, so is not the place for routine requests for new categories.
Given the conflicting descriptions, it isn't particularly surprising that at the moment category requests end up in various different places.