"The indigenous Malayo-Polynesian Taiwanese" are in fact technically not "Malayo-Polynesian". More precise terms would be "Austronesian" or, better yet, "Formosan". The Formosan languages constitute first-order branches (Tsouic, Atayalic, Paiwanic) of the Austronesian language family. MP is another fourth branch. To say that Formosans are MP is like saying that sisters are their brother's daughters. Although MP was used in the past to refer to Austronesian as a whole (since most AN languages are MP), this usage is now obsolete among specialist linguists.