That's what Woody Hearn from GU Comics found inside of the Bioware Tems of Service on the Star Wars: The Old Republic website. The paragraph in question (found in section 7 of the terms) essentially states that all fan art derived from any intellectual property of LucasArts and/or Bioware is explicitly the property of LucasArts and/or Bioware. So that stormtrooper picture that you drew? Yeah, it belongs to LucasArts.
Hearn has already explicitly stated that GU Comics won't be featuring any more Star Wars: The Old Republic or other LucasArts / Bioware titles until the policy changes. While he is covered under the fair use law for satire, any other pieces drawn by other artists may not be.