Using HTML in a textarea when calling form hook

I'm trying to add a disclaimer display in a module theme, but having trouble displaying HTML being passed. My intent is to display the disclaimer with the code below and have a required checkbox acknowledgment. The code below displays <p><strong>Test</strong></p> on the page, how do I change the output format when using hook_form?

    $form['signup_form_data']['disclaimer'] = array(
    '#type' => 'textarea',
    '#title' => check_plain($type->body_label),
    '#attributes' => array('readonly' => 'readonly'),
    '#rows' => 20,
    '#default_value' => check_markup('<strong>Test</strong>','Full HTML'),
    '#required' => false
    );