SAN JOSE CALIE--Gary Kremen has prevailed in his two-year legal battle to win back tights to the lucrative and heavily traveled www.sex.com Web domain. A federal judge ruled the sites current operator, ex-convict Stephen Cohen, now residing in Tijuana, Mexico, most likely stole the tights to the domain name five years ago. Kremens dilemma was the focus last spring of a Brandweek article by Philip Van Munching, who has known him since l981, highlighting the branding-rights perils of cyberspace (Brandweek, June 19).