Set every new BP doc to pending status.

bp_docs_mark_all_new_docs_as_pending.php

<?php
/**
 * Mark all new docs as pending.
 *
 * @param array  $r    The parameters to be used in wp_insert_post().
 * @param object $this The BP_Docs_Query object.
 * @param array  $args The passed and filtered parameters for the doc
 *                     about to be saved.
 */
function bpdocs_support_mark_all_as_pending( $save_args, $bdq_object, $passed_args ) {
	if ( ! current_user_can( 'bp_moderate' ) && $bdq_object->is_new_doc ) {
		// Set the post status as "pending".
		$save_args['post_status'] = 'bp_docs_pending';
	}
	return $save_args;
}
add_filter( 'bp_docs_post_args_before_save', 'bpdocs_support_mark_all_as_pending', 10, 3 );