It sounds like he hesitated since it's a question he's surely not authorized to confirm or deny. The IGN guy continued to talk, asking if they had to alter the story to fit anyone in from SC4/5, which he then immediately said no to. You can look at that as him saying no because we got Talim despite age issues, or Zasa despite the fact he's a SC3 character, and the addition of Groh and Geralt who obviously weren't in the SC1 story.
But they've already shown a timeline that stretches through SC1-SC4. They don't have to include all characters (and probably won't), but they don't need to change anything for Talim if her story matches take place during SC2 or after.