Is this block safe from code injection exploit?

Thanks good people here, I have create a simple module which generate two blocks as follows:

function myblockmodule_block_info(){
    $block['myadblocks'] = array(
        'info' => t('My first ad blcoks'),
        'cache' =>  DRUPAL_CACHE_GLOBAL,
    );

    $block['myadblocks2'] = array(
        'info' => t('My second ad blcoks'),
        'cache' =>  DRUPAL_CACHE_GLOBAL,
    );
    return $block;
}

/**
 * Define what our block is going to look like.
 * Implements hook_block_view().
 */
function myblockmodule_block_view($block_key){
    $block = array();

    if($block_key == 'myadblocks'){ //We only want to define the content of OUR block
        //This is the title of the block.
        $block['subject'] = '';

        //Define the block content.
        $block['content'] = '<script>some ad js comes here</script>';
    }
    elseif ($block_key == 'myadblocks2') {
      $block['subject'] = '';
      $block['content'] = '<script>some other ad js</script>';
    }

    return $block;
}

My intention is to user these blocks instead of my current blocks that were volnurable to to script injection.

However, I am not sure the new module-based blocks will be more secure than the old admin-generated blocks. So appreciate your critical review of the module above.