What is Christian Malcolm´s highest react when his time was below 20.58?
CREATE TABLE "heat_2" (
  "rank" real,
  "lane" real,
  "athlete" text,
  "nationality" text,
  "time" real,
  "react" real
);
SELECT MAX("react") FROM "heat_2" WHERE "time"<20.58 AND "athlete"='christian malcolm';