In the Packer build you can have your provisioning script wait for the cloud-init to finish because you're not delaying a production scaleout; you've got all the time in the world. It's true that this article still gets written, but I don't think OP was suggesting otherwise. Building fully baked images rather than installing things on production startup avoids all sorts of flakiness.

Incidentally the author's suggestions are not that good, and not what I would suggest. He should be waiting for cloud-init to finish, not just apt:

    cloud-init status --wait

Before I knew about that, I used the following, which is still better than what the author suggests:

    while [ ! -f /var/lib/cloud/instance/boot-finished ]; do echo 'Waiting for cloud-init...'; sleep 1; done

Other stuff happens in cloud-init besides locking apt for awhile, and these will wait for all of it to finish.