Cake3, beforeFilterでredirectが効かない時があるっぽい

<?php
namespace App\Controller;

class PostsController extends AppController
{

    public function beforeFilter(Event $event)
    {
        parent::beforeFilter($event);

        $this->forceRedirectToStep1();
    }

    public function step1()
    {
    }

    public function step2()
    {
        exit;
    }

    private function forceRedirectToStep1()
    {
        if ($this->getParam('action') != 'step1') {
            $this->redirect(['action' => 'step1']);
        }
    }
}

step2() で exit を書いてたら動かなかった