bp_blogs_can_comment_reply( bool $retval, object|array $comment )

function bp_blogs_can_comment_reply( $retval, $comment ) {
	if ( is_array( $comment ) ) {
		$comment = (object) $comment;
	}

	// Check comment depth and disable if depth is too large.
	if ( isset( buddypress()->blogs->thread_depth[$comment->item_id] ) ){
		if ( bp_activity_get_comment_depth( $comment ) >= buddypress()->blogs->thread_depth[$comment->item_id] ) {
			$retval = false;
		}
	}

	// Check if we should disable activity replies based on the parent activity.
	if ( isset( buddypress()->blogs->allow_comments[$comment->item_id] ) ){
		// The blog post has closed off commenting, so we should disable all activity
		// comments under the parent 'new_blog_post' activity entry.
		if ( empty( buddypress()->blogs->allow_comments[$comment->item_id] ) ) {
			$retval = false;
		}
	}

	// If comments need moderation, disable activity commenting.
	if ( ! empty( buddypress()->blogs->comment_moderation[$comment->item_id] ) ) {
		$retval = false;
	}

	return $retval;
}