As per accordion api active is meant for "Which panel is currently open." , it takes false (to collapse all) or other options are numeric like 1, 2 to active either the first or second respectively
Logically it will not be a bug because as accordion is meant to collapse the menu. You can post to their forum for better clarification
I tried using active: false/true
but they both behave the same. http://jsfiddle.net/raunakkathuria/sc7uL/1/
See this blog for explanation regarding this http://forum.jquery.com/topic/expand-all-zones-for-an-accordion