In case any of you are still wondering, the policy that wasn't explicitly stated is no money/BTC is allowed to be withdrawn within 24 hours of an email (or possible other info) changes. Here are their exact words:
Mt.Gox Support, Apr 10 15:10 (JST):
Thank you for contacting us. Unfortunately, the hold is for 24 hours after changing your email address for security reasons. Please wait 3 more hours until your hold is lifted from our system. We apologize for any inconvenience caused.