ccplim - thats by design. To change ownership of the article would require changing post counts and such and I never coded it for that.
Deriel - you would need to add another field to geek_articles, add an input field into the GAS_article_options template, edit your newthread.php and editthread.php to catch it, edit your functions_gas.php to pass the new field along and update/insert it into the table.
It really sounds like a lot more work than it is