Q: change a post status when users update posts? Is there an efficient way to change a post status from 'published' to 'draft' when a user of a certain type tries to update their posts. I tried something along these lines
function change_post_status($post_id)
{
  if(current_user_can('rolename'))
  {
    $current_post = get_post( $post_id, 'ARRAY_A' );
    $current_post['post_status'] = 'draft';
    wp_update_post($current_post);
  }
}

add_action('pre_post_update','change_post_status'); 

The code looks good to me but for some reason it doesnt work properly and I think it creates an endless loop(forcing me to restart my SQL server). 

A: Have you tried to use "wp_insert_post_data" instead of "pre_post_update"?

A: Since your logic is based on role, just not give it publish_posts capability? The way native Contributor role works.

A: So I ended up using the wp_insert_post_data filter and came up with the following, which after testing, seems to be working properly.
add_filter('wp_insert_post_data', 'change_post_status', '99');

function change_post_status($data)
{
    if( (current_user_can('role')) && ($data['post_type'] == 'custom_post_type') )
    {
        if(defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) return;
        //then set the fields you want to update
        $data['post_status'] = 'draft';     
    }
    return $data;
}


A: I would like to add one more issue. When you use the code above, it will happen to EVERY post, also if you do an update in the backend! Because wp_insert_post_data is triggered eveytime a post is updated, so also if e.g. the admin wants to publish a post - it will automatically trigger again, and set the post to draft. So it will not be possible to publist anymore.
Here a modified code which worked for me, check if we are in the admin backend:

function change_post_status( $data, $postarr ) {
      $data[ 'post_status' ] = 'draft';
      return $data;
}
if (!(is_admin())) {
  add_filter( 'wp_insert_post_data' , 'change_post_status' , '99', 2 );
}

