The policies enforced by particular offices (often based on an excess of caution, and often based on mythology of law rather than actual legal advice) are a different thing than the law. It absolutely is
not illegal to provide answers to that question more directly when selling real estate (and, in fact, most agents I've dealt with or encountered will, though rather than providing their opinion they will rather directly provide statistical data which answers that question -- and others -- with comparative information; the package I got from the agent for the last house I considered buying included not only school performance information for the neighborhood compared to other areas in the region, but also income information, family size information, and other demographics.)
Providing a bare and unsupported simple subjective "good" or "bad" answer is probably more legally dangerous than providing factual information, not because "good schools" is dog whistle for "white neighborhood" (in fact, its neither illegal nor uncommon to provide factual information which fairly directly gives information about ethnic/racial demographics), but because someone else might convince a court that your description was slanted because you were trying to steer the buyer based on your perception of their racial fit, rather than trying to provide them factual information about the existing character of the neighborhood which might be relevant to their decision.