It is entirely appropriate to consider Apple's conduct as anti-competitive and/or acting as part of a cartel, without asserting that the appropriate remedy is an injunction allowing Facebook to utilize user's unique device ID's to the benefit of Facebook's ads systems for ad targeting.

In other words, this particular case may help elucidate Apple's dominance/influence on the market, but that does not necessarily mean that the privacy changes in and of themselves are the foundational antitrust issue.