The EPIC Storm is a combo deck with almost no creatures, so most of our disruptive sideboard cards aren't useful; the extra Swords to Plowshares can answer their rare creature threats like Runehorn Hellkite if it gets flashed in, or more importantly buy time against a hasty finisher. This matchup comes down to a race: either we assemble Cephalid Illusionist's mill plan or Dread Return reanimation before they combo off with Tendrils of Agony or Beseech the Mirror, so keep Force of Will up to protect our own combo turn. Shuko offers no value against a deck we aren't attacking.