Bill Gross is no longer running the world’s biggest bond fund, but one thing hasn’t changed: his love for Mexico. In a Twitter post Thursday, Gross said the country offered the “most attractive yields in the world,” a week after proclaiming on a CNBC interview that Mexico’s government debt was his “best” recent trade idea. The 71-year-old Gross, who departed Pacific Investment Management Co. in September, emerged as a Mexico bull three years ago when he praised its bonds and currency as the nation prepared sweeping changes to its energy policies.