The preamble distinguishes between stalking and stalking on the basis of sex (only the latter of which falls under Title IX):
Recognition that stalking does not always relate to sex and therefore do not always fall under Title IX (ex. celebrity stalking)
See footnote 772 on 30172–“Stalking that does not constitute sexual harassment because it is not ‘on the basis of sex’ may be prohibited and addressed under a recipient’s non-Title IX codes of conduct”