bbPress.org

Untested. auto-closes a topic on-the-fly when someone visits it and it’s last post is 90 days old (adjustable)

add_action('bb_head','auto_close_topic');

function auto_close_topic() {

global $topic;

if (is_topic() && $topic->topic_open===1) {

$old=time()-3600*24*90; // 90 days default

if (strtotime($topic->topic_time)<$old) {

bb_close_topic($topic->topic_id);

$topic->topic_open=0;  // just in case the cache doesn't clear

}

}

}