He’s referring to how you need an iPhone or iPad to set up the Apple TV; you can’t sign in to it without one. It’s an odd ‘overlook’ from Apple.
Apologies, they did for an iCloud Update on Apple TV: https://timesofindia.indiatimes.com/gadgets-news/apple-tv-users-may-need-an-iphone-or-ipad-to-accept-icloud-terms-and-conditions/articleshow/97063589.cms
Exactly what I was thinking!