Look, I’m not defending Apple here, I have my fair share of gripes with them (especially under Tim Cook), but let’s not assume to know what went into this decision. If YouTube is throwing copyright law and other shit at you, even if you think they’re wrong it’s probably not worth it (in terms of cost and broken relationships) to fight it. For all we know they could’ve threatened to removed the official app on iOS, which will undoubtedly have more users.